Hello everyone,
I am one of the guys from the Stalker RP in CS2D project.

So, after hosting our server (with a VPS service), some players (including me) can't find it in the list of servers.
I tried finding a solution by using a VPN to change my IP, and deactivating my antivirus, but it didn't change anything.

Did someone have the same problem? Can someone help me please?

Thanks in advance

I moved your thread to the right section as this isn't an Off-Topic question.

See
https://www.cs2d.com/faq.php?show=net_noentry#net_noentry

It's weird though if some people see your server and are able to join. That would imply that all your settings are probably already correct.