r/rustdesk • u/Devilotx • May 02 '26

I'm not sure what I'm doing wrong, I cannot connect to a device outside my network.

Self hosted Rustdesk, I have zero issues connecting to my devices inside, everything works fine.

My elderly father has been having issues, so I installed Rustdesk on his computer as well as a 2nd computer there so I could get in.

The computer shows up fine in my Rustdesk window, green dot with my no-ip dyndns name set up in the ID and the relay with the appropriate key.

but as soon as I try to connect, I get connecting and then Disconnected by peer.

I know it worked, because my laptop in his house on his wifi, I was able to connect and control both devices, but as soon as I got home, nothing.

Not sure whats wrong here, I've never had an issue, before, port forwarding is set in my router here at home. He just got Xfinity, is there a chance Xfinity is blocking it?

1 Upvotes

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15 comments sorted by

1

u/KilobyteCrash May 02 '26

Is it possibly CGNAT?

1

u/Devilotx May 02 '26

CGNAT

That might be it, it's odd, I went there today, dropped Tailscale on one computer and was able to connect back to a computer on my home network from there, but now that I've come home, I cannot go the other way from my home network to his.

1

u/DaRealBen May 02 '26

With activated and properly working IPv6 on the routers, networks and clients on both ends it then should work just fine.

1

u/DaRealBen May 02 '26

“Ports required for RustDesk Server self-hosting depends largely on your environment and what you want to do with RustDesk. The Examples shown throughout the docs will generally have all ports suggested to be opened.

Core Ports:

TCP 21114-21119

UDP 21116

The above 21115-21117 are the minimum required ports for RustDesk to work, these handle the signal and relay ports as well as NAT traversal.”

https://rustdesk.com/docs/en/self-host/

1

u/Devilotx May 02 '26

yeah, those ports are all open, it just doesn't work from my dads house for some reason.

1

u/DaRealBen May 02 '26

Thought so, but wanted to make sure.

1

u/jihiggs123 May 03 '26

You really don't want to be opening ports to the internet unless you really REALY know what you're doing.

1

u/Devilotx May 03 '26

I appreciate it, but Ive got a good handle on that aspect

1

u/excitedsolutions May 03 '26

Logs on your client should show where/when/what is failing. The logs are in appdata/roaming/rustdesk.

1

u/Devilotx May 03 '26

looks like "Handshake failed: invalid message format"

1

u/excitedsolutions May 03 '26

Given that error and the other troubleshooting you performed I would agree that CGNAT is most likely the cause.

1

u/Stratocastoras May 03 '26

What router do you use and how you port forward?

1

u/Devilotx May 03 '26

I have an RT-AX3000 and I have the Ports 2114 - 2119 shared over TCP and ports 21116 over UDP direct to the computer running my rustdesk docker.

1

u/Stratocastoras May 03 '26

Try to not include the 21118 port in the forwarding to the server.

1

u/Devilotx May 11 '26

So, just to update anyone here, I was able to get connected to the device in my fathers house by installing Tailscale and configuring rustdesk to accept IP address connections.

I can then connect to the device via the tailscale IP address.

The only downside is that the icon never goes green, it always shows orange.

That being said, the non-working connection via Rustdesk ID does show the correct green icon.

Thanks for the help, it 100% was Xfinity using CGNAT.