I can´t connect with the LFS Server. My ISP said, probably the LFS is blocking my IP. Is this possible? I race with demo for months and just some weeks after I bought the S2 I started to have problems.

I'd say check your firewall permissions and stuff or send an e-mail to the devs.

Even without firewall, it´s impossible to connect...

Many possible issues here. One is that there is a firewall. There are the software firewalls that you can turn off, and there are hardware firewalls that you may have to punch holes in for LFS to work... but usually that is only the case if you are trying to run a server.

Find the master server IP address and send it a ping and see what happens.

Also, your ISP might have a proxy server upstream of you that is causing a problem, or they might have some form of firewall setup.

Another thing to check is all your IP settings and make sure that they are configured properly.

If the demo worked before, then S2 will work. It is not the game that is a problem.

Good luck and keep at it, you will figure it out.