2 PCs, 2 Steam accounts, 1 Wi-Fi router: can't play online in the same lobby at the same time

[voloshaninm]

Hello everyone! Maybe someone has faced this issue and can help. I have an optical terminal at home. There are two PCs connected to the internet via Wi-Fi, both have Steam installed, each with its own account. When trying to join an online game simultaneously (into the same lobby), one PC connects, but the other one gets a connection error. Googling results don't show this as a common problem; more often, there are comments that many people play like this (from one internet connection on different accounts) without any issues. I've disabled firewalls, specified the ports used for each game through properties in Steam, and in launch parameters — "+clientport 27007" (on the second PC I specified a different port).

What could be the issue? Do I have something set up incorrectly, or is this normal because they have the same external IP, which causes a collision?

[Junki]

Does this happen in all games or is it just one specific game you've attempted?
It could be an issue with the games networking rather than your own, which would be a shame, but a possibility.

[voloshaninm]

I tried L4D2, it was possible to connect there only in the "local server" mode, and a friend from another city was also able to join us. But we couldn't get to his dedicated server anymore, or rather one of us couldn't. And we also tried the Devour game, we couldn't connect there either. And which game should not have such problems - can you tell me? So that I can check if I have a problem or in the games I have chosen

[Junki]

Well given that you've tried multiple games with the same outcome, I doubt it's something to do with the games you're playing. It sounds like something funky on your internal network, which would be something for Google I'm afraid.

[voloshaninm]

Thank you. I have solved my problem. In the router settings, I disabled UPnP and everything worked as it should.