Syncing between two local PC's: why is all my data being sent to a Russian public IP as well?


I installed your product on two Windows machines on the same local LAN. Got the sync to work between the two, however, at the same time, I am seeing all the data being simultaneously being ported through my firewall and to a Russian public IP address. ALL my data! Why is this happening?? I just want my data going between two PC’s. I killed the sharing and would like a detailed explanation please.

Thank you,


What IP address? I suspect, that for some reason relaying is used. Check the list at if the IP is on it. Your data is end to end encrypted, even when using relays.

Are the two devices in the same subnet, or are you maybe syncing one on LAN and one on Wifi with different subnets?

Two different subnets. One LAN, one Wifi.

Yeah, it’s in the list. Why relay at all? Why not just through my local vlans and call it a day?

I suspect this can be because of windows personal firewall (network places set to publiC?)…
try disabling relaying and setting the address of your machines manually.

Two different subnets probably means that udp broadcast (or multicast? Can’t remember which one synching uses for local discovery) isn’t forwarded, so synching isn’t able to discover the lan ip of your other device.

You can specify its ip manually if you want. Also read this:

Is the solution to disable relaying in Settings?

You can try disablingrelaying, but as I and others have said, Syncthing is only using relaying because it cannot figure out a way to connect directly to the other device.

If you disable relaying without fixing the underlying issue, then your devices simply won’t connect.

Would it ever use relaying if all the devices were on a single home network?

Normally, no. However if there was a firewall blocking direct connections, then it would not be able to establish a direct connection, and would resort to relaying.

The OP doesn’t have a single home network: he has two different subnets, which is probably blocking Syncthing’s local discovery mechanism.

Ah, that latter part clarifies it. Thanks.

Plus, marking your home network as public on windows, kills discovery. I sadly couldn’t find a way to reclassify a network on Windows 10.

I found that option. I’ll try and dig it out when I get home.

I know there is supposed to be a thing to click on in the homegroup view, thats what I found on all articles related to this on the internet, but on my build of windows, the blue link in the yellow box is simply not there.

1 Like

I never found a way to change the setting directly, but if you enable Network discovery (Find devices and content) it will tell you that isn’t possible on a Public network and then ask if you want to change it to Private.

In my experience, the Network settings panels look/act radically different depending upon what version of 10 you’re running as well as what settings you have enabled. If you don’t have the option to enable ‘Find devices…’ there, then just click on the network in Windows Explorer and that should prompt you.

This topic was automatically closed 30 days after the last reply. New replies are no longer allowed.