Asseto Corsa multiplayer doesn't work

[trodem]

Me and my Friendd both tried settiing up an assetto corsa server but it doesn't work.
All the time it says this

We both have done everything it wanted: Port forwarding, checking if it is getting blocked by AV or Firewall, and it still doesn't work.
We both have the same internet provider we may think its because of that ( we have a Fritzbox it's a german router)
anyne got an idea?

 

[petervandamned]

for me and my fritzbox it's working 100%
thnks to this guide