I do not have a thompson router and I have this issue. It is not my interent connection because I have tested it and it works fine for all other games and it is also not my router because this problem has never happened before. The only constant in this problem is arma 3 itself. People using different routers and different setups are all experiencing the same "connecting failed" problems to which there seems to be no fix.

So please stop with the "its a thompson router" problem, it might mislead the developers to miss this issue and take it as a hardware problem and not an issue with the game itself for which is clearly is.