Why can't PCs see each other outside the LAN (Syncthing)?

Question

Data synchronization

Good afternoon!
Available: 5 PCs with Windows 7 SP 1 (Ultimate). All have Syncthing installed . The settings are set in accordance with the Getting Started Guide : UPnP - On, Global Discovery - On, Local Discovery - On. Port forwarded to one of the PCs (let's call it "server") to synchronize with a PC (let's call it "home") outside the local network via the Internet. Firewalls are completely disabled, the global discovery server finds both the server and the house, but they do not connect to each other - they do not see each other.
Maybe someone faced a similar problem?

Answer 1

For starters, the IP on the server should most likely be "white", that is, not behind the Nat provider

Answer 2

I think the first thing to do is to deal with port forwarding on all computers where possible. And only then, based on the results, see why there is no connection in Syncthing. The downloading computer is not required to have a white IP, only a distributing one. But, if the initiator of the connection is the distributor, then it should be at least the other way around, or both computers have a white IP (in the sense, even though dynamic, but not behind NAT). A static IP from the provider is good, but it is not needed for these purposes if there is a white dynamic one (usually so on ADSL).
If all computers or most of them are behind NAT, then you can do this trick with ordinary torrent clients rutracker.org/forum/viewtopic.php?t=4494268