After I tried the free trial of Avast Internet Security I have had some problems entering games requiring internet connection.
I have tried to make exceptions in the settings>antivirus>exceptions but it didn’t help.
Can anyone help me?
well, if you have same problem that i had, then do you have enabled your hardened mode and is it on Moderate or Aggressive mode?
or, you could check your avast firewall.
avast! main window - Tools - Firewall - Program rules
It worked! Thank you very much! 
You’re welcome.