Ah, is that (max 20 connections) the reason why I can't connect to the node? What will happen to the coins that have been mined already?
The hard limit of 20 connections is set because my host is slow and can't support more thread simultaneously. And there are only few hosts with public ip. That's why almost no one can't connect to another. Already mined coins may be recalculated be the algorithm after the synchronization.