Any info about how Unreal uses Steam?


This is not an Unreal Engine bug or anything like that, I think it’s something about my PC.
The game I build worked perfectly on my PC in LAN, and I can connect my laptop with my pc via LAN with no problem.
The problem is about Steam. When I try to connect my PC to my laptop via Steam(or vice-versa), the search always returns no session. But then I send the game build to a friend of mine, and they can connect via steam to my laptop with no problem, but not my PC.
All other Steam games worked fine on my PC and the same friend plays Steam games with me almost every day.

So my question is, is there any Info regarding how Steam integrated Unreal game works? Something like which port it uses for steam server connection, which port is used for game sync, etc. So at least I can have somewhere to start looking for the problem.

All info is appreciated!