[graf_von_anonym]

Hmm. The fact that you can ping the default gateway would tend to suggest you're not suffering from a classic "valid IP no throughput" scenario, but that might be me being unclear.

What make/model of modem are you using? What do you get when you click on 'Connection' up at the top? You don't need to post your IP address. It might be an idea to have a little check of your power levels, but I'm not convinced they are a factor.