---
title: "Network Sync"
description: "Set up synchronized video playback across multiple computers on your local network with FloSync server/client mode."
url: "https://flosync.com/docs/network-sync/"
lang: "en"
updated: "2026-10-17"
---

# Network Sync

Network sync allows you to synchronize video playback across multiple computers on the same network. This is essential for large installations where a single computer can't drive all the required screens.

## Overview

Network sync uses a server/client model:

- **Server**: One computer acts as the master and leads playback for the others
- **Clients**: Other computers connect to the server and follow it

Every computer needs its own copy of the same video, and all of them must be on the same local network.

![Four computers on one local network, each driving two panels of an eight screen video wall, with a single video continuing across the whole wall](https://flosync.com/images/diagrams/screens-four-computers.svg)

*Four computers driving eight screens as one wall. Each machine plays its own copy of the same video and covers its own region; the network keeps them together. Each outlined group is one computer's pair of screens.*

[The finished wall as viewers see it: one video playing across all eight screens.](https://flosync.com/images/diagrams/screens-four-computers-preview.mp4)

## When to Use Network Sync

Network sync is designed for scenarios where:

- You have more screens than one computer can support
- Screens are physically distant (different rooms, different floors)
- You need redundancy (multiple computers for reliability)
- Your video wall is larger than one computer's GPU can handle

### Example Setups

**Retail Store**

- Server in back office driving main entrance screen
- Client computers at each department driving local screens
- All showing synchronized promotional content

**Event Venue**

- Server at tech booth
- Clients driving screens throughout the venue
- Synchronized playback for live event content

**Large Video Wall**

- Multiple computers, each driving a section of the wall
- One server coordinates timing
- Each computer uses **Global Canvas Extension** to define its position
- Appears as one seamless screen

## Requirements

Before setting up network sync:

1. **Same network**: All computers must be on the same local network (same subnet)
2. **Same video**: Each computer needs its own copy of the same video. The filename does not have to match, but the content does (clients can [import content directly from the server](https://flosync.com/docs/network-sync/#importing-from-server))
3. **Network ports**: FloSync uses two. **UDP port 9201** carries playback sync, and **TCP port 9202** carries content import between machines. Allow both, or sync will work while importing content from the server silently fails
4. **Firewall**: Allow FloSync through your firewall on all computers

## Setting Up the Server

The server is the "master" that other computers sync to.

### Step 1: Load Your Video

1. Open FloSync on the computer that will be the server
2. Load your video file by dragging it onto any screen box
3. Optionally, use the timeline to seek to your desired starting position

### Step 2: Start the Server

1. Click the **Server icon** (tower icon) in the top bar
2. The icon lights up bright lime, indicating server mode is active
3. FloSync is now leading playback for the network
4. The status bar at the bottom will show "Server"

![The control panel in Independent mode with a beach video on Display 1 and Display 2 empty, the server icon lit in the toolbar and Server in the status bar.](https://flosync.com/images/screenshots/docs-network-sync-server-active.jpg)

*This computer is now the server, and clients can find it.*

### Server Behavior

Once running as server:

- All connected clients follow the server's playback
- Play, pause and seek on the server apply to every client
- The server computer controls playback for all connected clients

### Controller Mode (Server-Only Feature)

When running as a server, you have access to **Controller mode**, a Go Live option that lets you control remote displays without creating fullscreen windows on your local machine.

**What it does**:

- Clients go live and stay in sync exactly as they would in normal Go Live
- Content plays in the composer's screen boxes instead of fullscreen
- All playback controls remain active (play, pause, scrub, scene navigation)
- Status bar shows "Live (Controller)" with an orange indicator

**When to use it**:

- Operating a video wall from a laptop at a control booth
- Managing displays at a trade show while keeping your screen available
- Testing network sync setup without going fullscreen locally
- Running a live show where the operator needs to see and control content

**How to use it**:

1. Start server mode (tower icon lit)
2. Load your content
3. Click the **Go Live** dropdown
4. Select **Go Live (Controller)**

Go Live

*The Go Live button, at the bottom right of the composer window.*

If Controller mode is selected while you are connected to another server as a client, FloSync will ask before switching this machine to server mode.

Clients connected to your server will go live normally with fullscreen windows, while your server machine stays in the composer view.

See [Controller Mode in Go Live](https://flosync.com/docs/go-live/#controller-mode) for more details.

## Setting Up Clients

Clients discover and connect to the server automatically.

### Step 1: Load the Same Video

1. Open FloSync on each client computer
2. Load the **same video file** that's on the server by dragging it onto a screen box
3. The filename doesn't need to match, but the content must be identical

> **Tip**: You can skip this step by using the [Import on Connect](https://flosync.com/docs/network-sync/#import-on-connect) checkboxes when connecting to the server. FloSync will copy the server's scenes and content files to your machine automatically.

> **Important**: Clients must have the same video loaded. If the lengths differ, that computer will not follow the server's timeline. It carries on playing its own video on its own, which looks like one screen quietly doing its own thing rather than an error.

### Step 2: Connect to Server

1. Click the **Client icon** (Wi-Fi icon) in the top bar
2. FloSync will start searching for servers on the network
3. A dialog appears showing discovered servers

![The Select Server dialog listing one server, WALL-PC-1, with the four import boxes Global canvas, Scenes, Content files and Audio settings all checked.](https://flosync.com/images/screenshots/docs-network-sync-discovery-dialog.png)

*One server found. Yours should show its computer name here.*

### Step 3: Select Your Server

1. Click on the server you want to connect to
2. FloSync will connect and begin syncing
3. The client icon will turn blue, indicating connected status
4. The status bar at the bottom will show "Connected to \[server name\]"

### Import on Connect

The server selection dialog has an **Import from server...** section with optional checkboxes that let you pull the server's configuration during connection:

- **Global canvas** imports the server's canvas layout so your displays match. This one is skipped if the server runs a different operating system than you do (see [Mixed macOS and Windows walls](https://flosync.com/docs/network-sync/#mixed-macos-and-windows-walls)).
- **Scenes** imports the server's scene list, including display modes and scheduling.
- **Content files** downloads the server's media files to your machine and automatically enables Scenes.
- **Audio settings** imports each scene's audio on/off state, and also enables Scenes, since audio is stored per scene.

This is the fastest way to set up a new client: check all four boxes, select a folder for the files, and the client is fully configured in one step.

### Mixed macOS and Windows Walls

A canvas cannot be copied between a Mac and a Windows PC. If you try, FloSync tells you so and leaves your canvas alone:

> Canvas import across platforms is not supported in this version. Configure the canvas locally instead.

Everything else still imports normally, including scenes, content files and audio settings. Only the canvas has to be entered by hand on each machine.

The reason is that the two systems do not count screen space the same way, so a number that is correct on one would put the wall in the wrong place on the other. Set the values on each machine against its own displays and the wall lines up.

Mixed fleets are supported. This is one setup step you do per machine rather than once on the server.

### Client Behavior

Once connected:

- The client follows the server's playback
- Play, pause and seek on the server apply here too
- Alignment is maintained for you automatically
- A sync quality indicator appears in the status bar, reading **Excellent**, **Good**, **Fair** or **Poor**. It reflects how steady your playback position has been, not a diagnosis of the cause. Excellent and Good are what a healthy install looks like. If you see Fair or Poor, the network is the sensible first thing to check (congestion, interference, or a Wi-Fi link where a cable would do), but it doesn't rule out a loaded machine, heavy content, or anything else in your setup
- Control playback from the server. Using the local controls on a client works against the server and gives you no useful result

## Importing from Server

Once connected as a client, you can import the server's configuration and content at any time, not just during initial connection.

### Import Menu

Click the **connected server icon** in the top bar to open the import menu:

- **Import Global Canvas** copies the server's canvas layout to your machine.
- **Import Scenes** copies the server's scene list, including display modes and scheduling settings.
- **Import Content** downloads media files from the server for all scenes.
- **Import Audio Settings** updates the audio on/off state of your existing scenes to match the server, leaving everything else about them alone.
- **Import All** does the canvas, the scenes and the content in one step. Audio settings are not included, so run **Import Audio Settings** afterwards if you want those too.

![The control panel on a client connected to WALL-PC-1 with the import menu open, listing Disconnect, Import Global Canvas, Import Scenes, Import Content, Import Audio Settings and Import All.](https://flosync.com/images/screenshots/docs-network-sync-client-connected.jpg)

*The import menu on a connected client.*

**Import Scenes** replaces your scene list with the server's. If you have more scenes locally than the server does, FloSync asks first and tells you how many will be removed.

### Importing Content for a Single Scene

Right-click any scene in the schedule panel and select **Import Content from Server** to download files for just that scene. You can also right-click a display box or the background area.

### How Content Import Works

1. FloSync checks which files the server has loaded
2. You choose a destination folder on your machine
3. If any files already exist, you can choose to overwrite or skip them
4. A progress dialog shows the download status with file count, progress bar, and time remaining
5. You can cancel at any time

The server only offers the files in its current schedule, and only to machines already connected to it. Nothing else on that computer is reachable.

> **Note**: Local HTML files cannot be transferred over the network and will be skipped during content import. Web pages loaded from a URL import normally.

> **Note**: Content import needs **TCP port 9202** open, which is separate from the port playback sync uses. If sync works but downloads never start, that port is the first thing to check.

## Network Sync in Action

Once your network sync is running:

### Starting Playback

1. Press play on the **server** computer
2. All connected clients will start playing
3. Playback remains synchronized

### Pausing

1. Press pause on the **server** computer
2. All clients will pause at the same position

### Seeking

1. Scrub the timeline on the **server** computer
2. All clients will seek to match

### Preview Scrub Sync

When you're still setting up and haven't gone live yet, scrubbing the timeline on the server automatically updates the preview on every connected client that has the same video loaded. This lets you verify that content and positioning look correct across all machines before going live.

A client whose video is a different length will not follow the scrub. That is a useful check in itself: if one preview stays put while the others move, that machine has the wrong file.

### Client Controls

Nothing stops you pressing play or pause on a client, but there is no good reason to. The result depends on what that machine is doing at the time and it is not something to build a workflow on.

Control playback from the server. That is the one arrangement that behaves predictably on every machine.

## Persistence and Auto-Reconnect

FloSync remembers your network sync configuration and automatically restores it when restarted.

### Server Persistence

If FloSync is running as a server when you quit:

- On next launch, it automatically starts as server again
- No manual action required
- The server icon (tower) is lit immediately

### Client Auto-Reconnect

If FloSync is connected as a client when you quit:

- On next launch, it automatically searches for the last connected server
- The client icon (Wi-Fi) turns **orange** during search
- Status bar shows "Searching for \[server name\]..."
- When the server is found, connection is re-established automatically

### Server Disconnection Handling

If the server stops, quits, or becomes unreachable while a client is connected:

- The client notices on its own and drops back into searching
- The client icon turns **orange** (searching mode)
- Client mode stays on. You do not have to reconnect by hand
- When the server comes back online, the client reconnects automatically

This is useful for:

- Server restarts during configuration changes
- Brief network interruptions
- Server app crashes that are quickly resolved

### Manual Server Selection

When the client icon is orange (searching), you can click it to:

- **Stop Searching** - Exit client mode entirely
- **Keep Waiting** - Close the dialog but continue searching in the background
- **Select a different server** - If other servers are visible, click one to connect

## Interval Mode with Network Sync

When using Interval scheduling mode with network sync, clients automatically follow the server's scene transitions.

### How It Works

1. **Server controls scenes** - The server determines which interval scene is active
2. **Clients follow** - When the server transitions to a new scene (by timer or keyboard), clients receive the change
3. **Keyboard sync** - If someone presses arrow keys or number keys on the server, all clients switch to the same scene

### Setup

1. Configure the same interval schedule on server and client computers, or [import scenes from the server](https://flosync.com/docs/network-sync/#importing-from-server)
2. Load matching content in each scene, or [import content from the server](https://flosync.com/docs/network-sync/#importing-from-server)
3. Start server mode on the master computer
4. Connect clients to the server
5. Go Live on the server first, then on clients

### Notes

- Only video content syncs between computers; images and web pages display independently
- Cue scenes (manual advancement) work with network sync - press a key on the server to advance all computers
- Give every computer the same number of scenes in the same order. A client with a shorter list quietly stays on the scene it was already showing when the server moves to one it does not have, so a machine that stops changing scene usually means its scene list is short
- A client going live while the server is already running joins where the server is, both in the schedule and in the video

## Keeping Everything Aligned

FloSync keeps all your computers playing together automatically.

### Sync Tolerance

FloSync includes network sync tolerance controls in [Preferences](https://flosync.com/docs/preferences/) so you can tune behavior for your environment. In most setups, the default settings work well and keep playback visually aligned.

## Multi-Computer Video Walls

For video walls spanning multiple computers, combine **Network Sync** with **Global Canvas Extension** and **Spanned Mode**.

### How It Works

1. **Server leads playback** - One computer acts as the master
2. **All computers sync playback** - Clients follow the server's timeline
3. **Each computer shows its portion** - Global Canvas Extension defines which part each computer displays

### Setup Process

1. **On all computers**: Load the same video file
2. **On all computers**: Set display mode to **Spanned**. Global Canvas Extension is only available in Spanned mode, and cannot be changed while live
3. **On all computers**: Configure **Global Canvas Extension** for each computer's position in the wall
4. **On the server**: Click the server icon (tower) - lights up
5. **On clients**: Click the client icon (Wi-Fi) and connect to the server - turns blue
6. **On all computers**: Click **Go Live**

### Example: Eight-Screen Video Wall

For the eight-screen wall at the top of this page (four computers, each driving a side-by-side pair of 1920×1080 screens, two pairs in the top row and two in the bottom row):

![Four computers on one local network, each driving two panels of an eight screen video wall, with each computer's four extension values printed under its pair of screens](https://flosync.com/images/diagrams/screens-four-computers-labeled.svg)

*Each computer's extension values, as entered in the table below.*

**Canvas Extension settings:**

| Computer | Role | Extension (Top, Right, Bottom, Left) | Shows |
| --- | --- | --- | --- |
| PC 1 | Server | 0, 3840, 1080, 0 | Top left |
| PC 2 | Client | 0, 0, 1080, 3840 | Top right |
| PC 3 | Client | 1080, 3840, 0, 0 | Bottom left |
| PC 4 | Client | 1080, 0, 0, 3840 | Bottom right |

For a step-by-step walkthrough of this wall, from cabling the screens to going live, see [How to Sync One Video Across Eight Screens with Four PCs](https://flosync.com/blog/sync-video-across-eight-screens-four-pcs/).

**You don't have to type those numbers.** The Global Canvas Extension dialog has a **Quick Adjustments** row of one-click buttons that add or remove a screen's worth of space at a time: **1080p** steps by 1920 across and 1080 down, **4K** by 3840 and 2160. For PC 1 above, two presses of `+R` and one press of `+B` on the 1080p row give you 3840 to the right and 1080 below.

![The Global Canvas Extension dialog with Top 0, Right 3840, Bottom 1080 and Left 0, a Quick Adjustments row of 1080p and 4K buttons, and Reset, Cancel and Apply.](https://flosync.com/images/screenshots/docs-canvas-extension-dialog-pc1.png)

*PC 1's values: 3840 to the right and 1080 below.*

Values are set on each machine separately, against that machine's own displays, and cannot be copied from a Mac to a PC or the reverse. See [Mixed macOS and Windows walls](https://flosync.com/docs/network-sync/#mixed-macos-and-windows-walls).

### Visual Preview

Use the **Global Canvas Preview** (zoom icon) to visualize your setup:

- Dark areas show where other computers' screens are
- Grid lines help align to screen boundaries
- Drag your local screens to adjust position
- Hold **Shift** while dragging for free (non-grid) positioning

Here is the same eight-screen wall from each computer's point of view:

![FloSync on PC 1, showing content on its two screens in the wall's top-left and the rest of the canvas as virtual space.](https://flosync.com/images/screenshots/docs-network-sync-wall-pc1.jpg)

PC 1: top-left pair

![FloSync on PC 2, showing content on its two screens in the wall's top-right and the rest of the canvas as virtual space.](https://flosync.com/images/screenshots/docs-network-sync-wall-pc2.jpg)

PC 2: top-right pair

![FloSync on PC 3, showing content on its two screens in the wall's bottom-left and the rest of the canvas as virtual space.](https://flosync.com/images/screenshots/docs-network-sync-wall-pc3.jpg)

PC 3: bottom-left pair

![FloSync on PC 4, showing content on its two screens in the wall's bottom-right and the rest of the canvas as virtual space.](https://flosync.com/images/screenshots/docs-network-sync-wall-pc4.jpg)

PC 4: bottom-right pair

## Best Practices

1. **Test before the event**: Always test your full setup before going live
2. **Use wired networking for critical installs**: Wired connections are usually more stable than Wi-Fi. Wi-Fi is not a problem in itself, and for screens spread around a building it is often the sensible choice. Reach for a cable when the screens sit side by side, where small differences are easiest to notice
3. **Match video files exactly**: Keep the same source file on every machine
4. **Start server first**: Ensure the server is running before starting clients
5. **Monitor the sync log**: Open the **Log Panel** from the View menu to watch for sync issues
6. **Have a backup plan**: For critical installations, have spare equipment ready
7. **Go Live after connecting**: When using network sync, establish the connection before going live
8. **Configure canvas extension first**: For multi-computer video walls, set up Global Canvas Extension on each computer before going live
9. **Check both firewall ports**: UDP 9201 for playback sync, TCP 9202 for importing content from the server

## Troubleshooting Network Sync

### Server Not Found

**Symptoms**: Clients don't see the server in the discovery dialog

**Solutions**:

1. Verify both computers are on the same network/subnet
2. Check that the server has actually started (shows "Server" in status bar)
3. Temporarily disable firewalls to test
4. Verify UDP port 9201 is not blocked
5. Check the status bar for a message like *Server "Studio-PC" was skipped, incompatible FloSync version. Update both devices to sync.* A computer running a different FloSync version does not appear in the list at all, so an empty list plus that message means a version difference, not a network problem. Update every machine to the same version
6. If the client computer has both Wi-Fi and Ethernet active, turn one off. With two live connections the computer picks one on its own, and it may not be the one the server is on

### One Computer Ignores the Server

**Symptoms**: Everything connects, but one machine plays its own thing, or stays on one scene while the others change

**Solutions**:

1. Confirm that machine's video is the same length as the server's. If it isn't, it will play independently rather than report an error
2. Confirm it has the same scenes, in the same order, as the server
3. Scrub the timeline on the server before going live. Any preview that doesn't move has the wrong file

### Content Import Fails While Sync Works

**Symptoms**: The machines sync fine, but importing content from the server never starts or never finishes

**Solutions**:

1. Allow **TCP port 9202** through the firewall on the server. It is a different port from the one sync uses, so sync working tells you nothing about it
2. Check that the client is still connected. Only connected machines may download
3. Local HTML files are skipped by design. Web pages loaded from a URL import normally

### Sync Drifts Over Time

**Symptoms**: Clients gradually fall behind or ahead of the server

**Solutions**:

1. Check network quality (packet loss causes missed sync updates)
2. Adjust sync tolerance in Preferences if needed
3. Verify video files are identical (different encodes may have timing differences)
4. Check CPU load - overloaded systems may struggle to maintain sync

### Jerky/Stuttering Playback

**Symptoms**: Video stutters or jumps frequently

**Solutions**:

1. Increase sync tolerance in Preferences
2. Check network congestion
3. Verify hardware can handle the video decode
4. Use a wired network connection instead of Wi-Fi

### Connection Drops

**Symptoms**: Client disconnects from server intermittently

**Solutions**:

1. Check network stability
2. Verify server is still running
3. Check for IP address conflicts
4. Consider network switch/router quality for large installations

## Firewall Configuration

FloSync uses two ports:

| Port | Carries | Without it |
| --- | --- | --- |
| UDP 9201 | Finding other computers, and playback sync | Clients never find the server |
| TCP 9202 | Importing content from the server | Sync works, downloads fail |

Allowing the FloSync application through the firewall covers both. If your firewall is configured by port rather than by application, add both rules.

**macOS**: FloSync will prompt for permission on first use. If blocked, go to: System Settings > Network > Firewall > Options > Allow FloSync

**Windows**:

1. Open Windows Defender Firewall
2. Click "Allow an app through firewall"
3. Add FloSync and enable for Private networks