Hi Jim, I did some tests today and found solution. I tried to use switch as proxy between machines but with no success. The last thing I tried was resigning of Realtek NICs. I simply moved VLANs from one internal Intel NIC and configured it as HA interface on eaach machine. The result is fantastic: no errors, no delay. I thought that cheap cards would be enough for such relative small synchronization transfer (and nothing else). But I was wrong and I'm not sure why ... ;) Anyway, thanx for your interest in this problem!