One PC connects correctly to a remote server, the other PC not

Support
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Hi dear helpers,

at first I like to thank the developer(s) for this promising software. Great idea!

I just installed SyncThing and have a litte problem:

I can connect with my laptop ACER to a remote server SERVICE-PC and to a desktop UWE-PC in LAN. But I cannot connect with my desktop UWE-PC to the SERVICE-PC and vice versa.

(More than 2 images are not possible, because I’m a new user.) The connection between SERVICE-PC and ACER is possible.

What can I do to solve the problem, please?

Greetings,

merlinuwe

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Hi! The first guess is that firewalling or NAT is in the way. Take a look here and see if that helps any?

https://forum.syncthing.net/t/firewalls-and-port-forwards/166?source_topic_id=429
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Thanks for your answer, but today I had (at first) no problems (!) without changing anything: Every PC connected to each other. UPnP was and is still activated in my LANs Router. Then, after a while I got the same problems as yesterday. (The problems stay the same, when I completely deaktivate my local firewall on UWE-PC.) Here you see my open ports in the router.

Are they ok?

After a restart of UWE-PC I got: 10:25:59: Failed to create UPnP port mapping

Only a connection to ACER is possible, not to SERVICE-PC.

After a restart of ACER I got a connection to UWE-PC and SERVICE-PC. That’s ok.

After a restart of SERVICE-PC I got no connection to UWE-PC and UWE-PC didn’t got a connection to SERVICE-PC.

10:07:16: Connection to UWE-PC closed: WSARecv tcp 192.168.178.43:51611: Ein Verbindungsversuch ist fehlgeschlagen, da die Gegenstelle nach einer bestimmten Zeitspanne nicht richtig reagiert hat, oder die hergestellte Verbindung war fehlerhaft, da der verbundene Host nicht reagiert hat.

10:07:56: Connection to SERVICE-PC closed: WSARecv tcp 192.168.178.43:22000: Ein Verbindungsversuch ist fehlgeschlagen, da die Gegenstelle nach einer bestimmten Zeitspanne nicht richtig reagiert hat, oder die hergestellte Verbindung war fehlerhaft, da der verbundene Host nicht reagiert hat.

And here is the thing I think that caused the trouble:

If I restart syncthing at Uwe-PC, then I get the message 10:48:18: Failed to create UPnP port mapping

So why does the port mapping fail? (The local firewall is still off.) And when I restart again, until this messages doesn’t occure - I finally get all connections, that I expected.

Is this a problem of my router (a new Fritz!Box 7490) or the failing of a try to map the port via UPnP of syncthing or something else?

Greetings,

merlinuwe

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