Okay Guys...
The DNS-thing Stefan mentioned is totally rubbish, sorry for that.
Here is, what is the true problem:
Beginning last weeks ago, a Radio-Bot which is running on our server connecting to a server in the USA for validating the license stopped working, tracert (Start->Run-> Type "cmd" (without "") into cmd: tracert <domain>) showed me, that 1 and 1 (in Germany 1und1, 1&1) exactely one server of them is swallowing our signal. In fact I contacted Keyweb (our hoster) and 1and1 but 1and1 stalled us, mentioning they can't do anything (which of course appears to me as alibi because we are not customers of them). Today I talked to Keyweb to talk to 1and1 what they did, but they also said, that it is to see, that it presumably won't be succesful.
My hint: run tracert with i-mod-productions.com (in cmd type: "tracert i-mod-productions.com" without "") and check where the signal is stuck - if you are customer of 1and1 and it is stuck at a server of them, tell them, that you have problems to connect so they may solve the problem. I hope the pure quantity of customers may help, but we are f**ked atm, cause 1and1 jacknifes.