LAN servers are restricted to local clients (class C) when trying to play privately

Me and a friend are trying to play ghosthunt 2 and it says this error.
We tried setting sv_lan 0 and sv_lan 1 for both of us but to no avail.
What should we do?

Are you using a VPS? Or are you in the same room or same network?

sv_lan 0
changelevel map_xxxx

Yeah uh we managed to fix the problem.
When he hosted a listen server he unchecked the ‘Local Area Network’ thing.
We finished playing now.