Технические проблемы с Heroes III

Name: Heroes3
IP Address: 192.168.0.136 (this is the IP of the hosting machine on the LAN)
TCP Ports: 2300 - 2400, 28800 - 29100, 47624
UDP Ports: 2300 - 2400, 28800 - 29100, 47624
Inbound Filter : Allow All
Schedule : Always

I put 6073, 6667 and 47624 to trigger ports 2300-2400 and 28800-29100.

We didn't have enough time so we just tested it like start game, end turn, other player ends turn, etc...it worked fine. BUT! When we later started a game, and a turn was longer than 1-2 mins, the sending data freezed again.
I thought that the problem is my router closes the port because it sees that there is no dataflow. I got a program called PortTrigger, which sends data on the specified ports every 2 seconds. Still no luck, sending data freezes all the time. I tried changing the PortTrigger and Router Port Triggering options like I saw it on www.portforward.com, but I couldn't make it work.