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Connection Methods

Contop supports three connection methods for reaching your desktop from anywhere.

LAN (Local Network)​

The fastest option — use when your phone and desktop are on the same Wi-Fi network.

  • Latency: Under 10ms typical
  • Setup: None (auto-detected)
  • How it works: The QR code includes your desktop's LAN IP. WebRTC connects directly over the local network.

Tailscale (VPN Mesh)​

For remote access without exposing your desktop to the internet.

  • Latency: 20–100ms depending on proximity
  • Setup: Install Tailscale on both desktop and phone
  • How it works: The QR code includes your Tailscale IP (100.x.y.z range). Traffic is encrypted end-to-end through the Tailscale mesh.
  • Detection: Auto-detected via tailscale ip -4 CLI or by scanning network interfaces for 100.x.y.z addresses

Cloudflare Tunnel (Global Access)​

For access from anywhere in the world, no VPN required.

  • Latency: 50–200ms depending on region
  • Setup: None — cloudflared is auto-installed
  • How it works: The server starts a Cloudflare Tunnel on demand (when you generate a temporary QR code), creating a public WebSocket URL. The mobile app connects via this URL for signaling, then establishes a direct WebRTC P2P connection.
note

The Cloudflare Tunnel is only used for the initial WebRTC signaling (SDP/ICE exchange). Once the P2P connection is established, all data flows directly between your phone and desktop via WebRTC.

WebRTC P2P Encryption​

Regardless of connection method, all data between your phone and desktop is encrypted:

  • DTLS — Encrypts data channels
  • SRTP — Encrypts video stream
  • Certificate fingerprint — Verified during pairing via the QR code payload

STUN servers (Google's public STUN) are used for NAT traversal to establish the P2P connection.

Choosing the Right Method​

ScenarioRecommended Method
Same room / officeLAN
Home to officeTailscale
Coffee shop / travelCloudflare Tunnel
Maximum securityTailscale (no public exposure)
Quick one-time accessCloudflare Tunnel (temp QR)

Troubleshooting​

Can't connect via LAN​

  • Verify both devices are on the same network
  • Check if a firewall is blocking the server port (default 8000, configurable via CONTOP_PORT)
  • Try the desktop's IP directly: http://<desktop-ip>:8000/health

Tailscale not detected​

  • Run tailscale status on the desktop to verify it's connected
  • Ensure Tailscale is running on both devices
  • Check that the Tailscale IP is in the 100.x.y.z range

Cloudflare Tunnel fails​

  • Verify cloudflared is installed and in PATH
  • Check internet connectivity on the desktop
  • The tunnel may fail if Cloudflare's edge is unreachable

Related: WebRTC Transport · Device Management · Quick Start