I was playing LFS multiplayer just fine, then my computer reset for some reason and when I returned to LFS multiplayer to join a server, it would say "could not connect to master server". I don't know if the computer resetting had anything to do with this issue and i didn't mess with any of the firewall settings either. I'm not sure what to do or why this is happening. -Leo

You had no internet. It's so simple.

Try to ping "master.liveforspeed.net". If you can use the internet, but cannot ping this address, check your DNS, firewall and/or provider settings.