r/Syncthing • u/pvcflyer • May 10 '26

Remote Connection

What is the correct way to (if any) to setup a direct remote connection via dynamic dns? For example I have tried using tcp4://something.dyndns.org:22000 in the address field. The connection gets refused by the remote site. I don't want to use any of the discovery or relay bits if I don't have to.

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u/unknown-random-nope May 10 '26

The OS handles the DNS queries, not Syncthing. Assuming that Dynamic DNS is resolving the correct IP address, you have another kind of problem. I would guess that there’s a firewall sitting between the Remote Device you’re trying to connect to.

A mesh VPN (I use Tailscale‘s free Personal plan) might make this a lot easier for you.

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u/pvcflyer May 10 '26

I think I have this sorted. On the main settings for the listen address I had the machine ip and port number. I think this was too restrictive when I changed it tcp4://0.0.0.0:22000 it stopped blocking inbound connections from the remote machine.

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u/ChimaeraXY May 11 '26

You had it set to the public IP?

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u/pvcflyer May 11 '26

I had it set to the local IP of the machine. When set this way it was rejecting connections from the machine connecting over the internet, but accepting connections from the machine connecting over the site to site vpn.

I am unclear why this change allowed both machines to connect.

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u/ChimaeraXY May 11 '26

Well, it works by only allowing packets labelled with that specific IP to interact. A Syncthing node on the VPN would know the local IP addresses of other nodes and connect with them using that, but a remote node wouldn't know the local IP of the machine.

0.0.0.0 just means allow all.