The IB connection seems to be not very stable. It disconnected many times and I was sure it was not the fault of my ISP since other programs were working properly. Although it would reconnect after few minutes, it was very annoying. Does anyone know what is happening in IB?
I wouldn't be so sure it isn't your ISP.
IB's TWS checks for packet loss on a connection. If you have packet loss (ie. a connection that is losing some data in the transmission), the TWS will disconnect.
Before going further you should do a ping test and a trace route. You should also see how many hops it takes to go from your ISP to the IB servers.
It would also help if you said when you went down. The system resets each evening for about 1 hour. If you are on the US server it resets around 11:30 PM.
If you do not know how to do any of these tests, take a look on the IB tech forum on the IB website. If you can't find help, post a question.