Do servers block 2 PC clients on same router?

[Sulev]

Tried to duplicate FileZilla on my 2nd PC (on same router) to be safe against all odds. Entered same configuration and data as in the first PC.

Did not work on the 2nd PC and also ruined the connections on the 1st PC, which had previously worked perfectly and on which I changed absolutely nothing!?

Do servers on the other end get suspicious when two computers behind the same router try to connect, and block both?

If so, what's the remedy?

[botg]

Servers cannot tell how many devices might be behind a NAT router. With routers in general, at most a server can see how many IP addresses are used, but that is independent from the number of devices. Some servers might block addresses based on observable behavior such as the amount of concurrent connections or the amount of failed login attempts though.

If you think you are blocked by the server, you need to contact your server administrator or server hosting provider for assistance.

[boco]

For IPv4, all clients behind NAT usually share one public IP. Server bans on that IP will therefore affect all clients behind the NAT.

IPv6 clients only share the Interface prefix of the IPv6 address. NAT should not affect IPv6 addresses, so, a more precise ban is possible.

[Sulev]

Thanks for your advice!
After a day's wait, the connection problem on the 1st PC just disappeared and FileZilla runs as perfectly as it has always done. No idea why.