WebRTC Remote Control Guide

Larktun WebRTC remote control lets you use an iPhone or iPad to view and operate the current desktop of a Windows PC or Mac at home or in the office.

Set up Larktun networking first, and make sure the app can reach the target computer through that network. Installing the WebRTC Host provides the remote-control service; Larktun provides the network path between devices.

This guide covers two connection methods:

• Direct network access: install both the Larktun networking client and WebRTC Host on the target computer, then connect to its Larktun IP.
• Subnet access: reach the LAN through a Larktun subnet router and enter the target computer's LAN IP. The target still needs the WebRTC Host.

1. Download the Three Components

Open the Larktun website and go to the download page to get the appropriate software.

Component	Where to install it	Purpose
Larktun iPhone / iPad app	The iPhone or iPad initiating the connection	Joins the Larktun network inside the app and provides WebRTC remote control
Larktun networking client	The target Windows PC / Mac, or a subnet router	Connects the computer or subnet to the Larktun network
WebRTC Host (Larktun Host)	Every Windows PC / Mac you want to control	Streams the desktop and sound, and receives remote input

On iPhone/iPad, follow the website's App Store link to install the Larktun app. On the computer, download both the Larktun client and WebRTC Host for the operating system you use.

What changes in subnet mode?

For direct access, the target computer runs both the Larktun client and WebRTC Host.

For subnet access, a router runs Larktun and forwards traffic into the LAN. The target computer does not need its own Larktun client, but every computer you want to control must have the WebRTC Host installed and running. Installing the Host only on the router does not provide desktop control of other computers.

2. Connect Your Network First

For a first connection, start with direct access:

1. Install the Larktun networking client on Windows or Mac, sign in to your Larktun account, and connect.
2. Open the iPhone/iPad app, sign in to the same account, and join the same network.
3. Confirm the computer is online and note its Larktun IP, such as 100.64.0.10.
4. If you use ACLs, confirm the current account or device is allowed to access the target.

See Desktop Client Operations for installation and sign-in, and Quick Start for initial network configuration.

For subnet access, install the Host as described below, then follow the subnet setup steps.

3. Install and Start the WebRTC Host

Windows

1. Get the Windows WebRTC Host installer from the download page and run the wizard.
2. Complete the administrator authorization requested by Windows.
3. Set the listening address and access token. The default listening address is :8771, and the default connection port is 8771.
4. Choose whether to capture system audio, retain the required firewall rules, and finish installation.
5. Confirm the LarktunWebRTCHost service is running. The installed Host runs as a Windows service and supports startup at boot.

You choose the access token and enter the same token later on iPhone/iPad. Use a token that is difficult to guess and configure token authentication for everyday use.

macOS

1. Get the Mac WebRTC Host .pkg installer from the download page and install it.
2. Open Larktun Host in the menu bar and go to its settings.
3. Set the listening address, access token, system audio capture, and launch-at-login preference.
4. In System Settings → Privacy & Security, allow Screen Recording and Accessibility for Larktun Host.
5. Restart the app as prompted, select Save and Start, and confirm the service is running.

Screen Recording provides the picture; Accessibility allows keyboard and mouse input. If only screen capture is authorized, you may be able to see the desktop without being able to operate it.

Choose a Listening Address

Scenario	Example	Meaning
Default configuration	:8771	Listen on available local interfaces; use a token and firewall rules to restrict access
Direct Larktun access only	100.64.0.10:8771	Bind to the computer's actual Larktun IP
Subnet access only	192.168.6.10:8771	Bind to the target's actual LAN IP so the subnet router can reach it

Replace the example with an address belonging to the target computer. Do not use 127.0.0.1, which permits local access only. For subnet access, the Host must listen on the reachable LAN interface rather than only a Larktun interface.

These settings do not require public router port forwarding. Retain the required local firewall rules and restrict access to the private networks you need.

4. Connect from iPhone / iPad

Once the app has joined the network and the Host is running:

1. Open WebRTC Remote in the app, or use the target device's remote-control shortcut.
2. Enter the connection details:

Field	Direct-access example	What to enter
Host	100.64.0.10	The computer's Larktun IP, without http:// or a port
Port	8771	The Host's actual listening port
Token	The token configured on the Host	Must match the target; this is separate from your Larktun password and networking Auth Key
Name	Office computer	Optional name for the favorite

3. Optionally enable Save to Favorites, then select Connect.
4. When the desktop appears, test a click, text input, and audio as needed.

Favorite connection tokens are stored in the iOS system Keychain. Reopen the favorite for subsequent connections.

Enter the address and port separately

Enter the IP in Host and 8771 in Port. Do not enter the combined 100.64.0.10:8771 in Host, or use the Larktun website address in place of the computer's IP.

5. Connect Using a Computer's LAN IP

Subnet access is useful when an office LAN contains several computers and a router, gateway, or Linux device already connects that LAN to Larktun.

Once subnet access works, enter the target computer's LAN IP in WebRTC Remote to connect. The target does not need to appear as its own Larktun device, but it must run the WebRTC Host and allow access from the subnet router.

Prepare the Subnet Route

This example uses:

Device or network	Example
Office LAN	192.168.6.0/24
Subnet router	An online Larktun-connected device that can reach this LAN
Target computer	192.168.6.10, with WebRTC Host installed
Client	An iPhone / iPad connected to the Larktun network

Complete these steps first:

1. Advertise the target subnet, such as 192.168.6.0/24, from the subnet router.
2. Approve the route in the Larktun console.
3. Configure ACLs to allow the current account or device to reach the remote-control services in that subnet.
4. Confirm the router itself can reach the target computer and that forwarding works.
5. Confirm the mobile app has a usable path to the subnet.

See Approve Subnet Routes for route advertisement, approval, ACLs, and forwarding. The mobile app uses its own networking; do not run the desktop CLI commands from that guide on iPhone/iPad.

Check the Host on the Target Computer

1. Install and run the WebRTC Host on 192.168.6.10.
2. Set an access token and make the Host reachable on the LAN, for example by listening on :8771 or 192.168.6.10:8771.
3. Keep the default embedded relay configuration, and ensure ACLs and the local firewall permit the required ports.

Alongside the connection port, subnet access may use the Host's embedded media relay:

Connection	Default	Purpose
Host connection	TCP 8771	Establish the remote session
Subnet media fallback	TCP 3478	Forward encrypted media through the Host's embedded TURN service
Direct media path	UDP ports used by ICE	Carry media directly when possible; grant the Host the required program-level firewall access

Allowing only 8771 can leave a session responding but stuck in negotiation. When troubleshooting subnet connections, also check that TCP 3478 is reachable and the embedded relay is enabled. With the default installation, the app attempts the appropriate path automatically. You do not need to purchase or deploy a separate public TURN service.

Allow these ports over Larktun or the required LAN path, without forwarding them to the public internet. If you customize the relay port, ensure the client configuration matches; keep defaults for initial setup.

Enter the LAN IP in the App

Open WebRTC Remote and enter:

Field	Subnet example
Host	192.168.6.10
Port	8771
Token	The token configured on the WebRTC Host at 192.168.6.10

Select Connect. Enter the target computer's IP, rather than the subnet router's IP. Even if the Host field says “tailnet IP,” it also accepts a LAN IP reachable through Larktun subnet routing.

If the target's IP changes, update the connection or favorite. A DHCP reservation on the LAN router can keep the address consistent.

6. Everyday Controls

• Touch and keyboard: operate the desktop with touch, the onscreen keyboard, and shortcuts. On iPad, you can also use an external keyboard, mouse, or trackpad.
• Text clipboard: copy and paste text to move addresses or commands between the app and computer.
• Quality: adjust picture quality and frame rate to the connection. On mobile data, try reducing quality before checking responsiveness again.
• Display switching: choose a monitor from the menu when the computer has multiple displays. One display is shown at a time.
• System audio: enable Host audio capture when needed, and check the iPhone/iPad volume and output device.
• Multiple devices: several devices can connect to one computer. One controls while the others watch. A newly joining device gains control; viewers can select Take Control to take over.

All connected devices see the same desktop. Share network access and tokens only with devices you trust to view and control it.

7. Troubleshooting

Symptom	What to check
Cannot connect after installing the Host	Confirm the app has joined the network; the target's Larktun client must be online for direct access, or the subnet router must be online for subnet access
Computer appears online but remote control fails	Device status does not prove the Host is running; check the service, listening address, port, token, ACLs, and firewall
Subnet computer is absent from the device list	Enter its LAN IP directly after confirming the route is approved, access is allowed, and the Host is running
Subnet route is approved but connection fails	Check the router's access to the target, forwarding configuration, and the target firewall
Subnet connection stays in negotiation	Check TCP 8771 and 3478 and the embedded relay; a successful Ping alone does not verify remote control
Token is rejected	Use the target Host's token, rather than a Larktun password or Auth Key
No picture on Mac	Check Screen Recording permission and restart Larktun Host as prompted
Mac desktop is visible but input fails	Check Accessibility permission and whether this device is currently view-only
Another device has taken control	Select Take Control in the viewing banner to switch the shared desktop's controller
Computer becomes unreachable while you are away	Check power, sleep, Host and Larktun startup settings; also check router availability for subnet access

On Mac, you can attempt remote unlocking after the user has logged in and subsequently locked the screen. The Host cannot capture the initial login screen after a restart before the first login. Verify unattended behavior on the target computer before relying on it.

8. Verify Your First Setup

1. Confirm the iPhone/iPad app is signed in and connected to Larktun.
2. Confirm the Windows/Mac WebRTC Host is installed, running, and configured with an access token.
3. For direct access, confirm the computer's Larktun client is online. For subnet access, confirm the router is online, the route is approved, and access is permitted.
4. Connect using the correct target IP, port, and token. View the desktop and actually test a click and text input.
5. Test audio, clipboard, and display switching as needed.
6. After setting up near the computer, reconnect using your phone's mobile data to verify access away from the LAN.

For other connectivity issues, see Common Troubleshooting. For the full set of mobile features, see the iOS App Overview.