Remote desktop over mobile data and CGNAT

A connection that works at home can fail when one computer is on mobile data. The reason is usually the network, not the app, and there are two dependable ways around it.

Why it fails

TideDesk always connects your two computers directly. To do that across the internet, each computer learns its public address, and both send small packets towards each other so their routers let the session through. This is often called hole punching.

It works through most home routers. It does not work through symmetric NAT, which is common on mobile data and on carrier-grade NAT (CGNAT), where many customers share one public address. There, the address a computer sees is not the one the other side can reach.

Many remote desktop tools hide this by sending the whole session through a relay server. TideDesk never does: your screen, sound and input never pass through anyone else’s server. So when a direct path cannot be opened, the connection fails rather than silently going through a third party.

What works

Use a VPN between the two computers

A mesh VPN such as Tailscale gives both computers addresses that reach each other wherever they are. Install it on both, then connect TideDesk to the host’s VPN address.

Forward one UDP port on the host’s router

If you control the router at the host’s location, forward UDP port 47800 to the host. The viewer can then reach it even from mobile data. This needs a router that offers port forwarding and a connection that is not itself behind CGNAT.

Check the basics first

• Both computers run a current TideDesk release; internet and device-ID connections need both on a current version.
• Windows Firewall allows tidedesk on the network you are using.
• Device IDs need both computers to reach rendezvous.tidedesk.app, unless they share a local network.

The full details are in the internet access guide.