Can't connect to some servers from two computers on one network

[texashopkins 0]

We've been playing Dayz for about a week and everything was fine. Two night ago however, we found we could not log in to the same server at the same time. It seemed to be getting confused and thinking we are the same machine.

In the lobby we don't see each other and we occupy the same spot. If one of us is already on and the other attempts to join, the first person gets the "no response for x seconds" and is eventually booted or sometimes the the new person never leaves the waiting for host screen but the existing user is fine.

This used to work but now doesn't on that server. Last night it failed on a couple of servers and in my testing today on several.

version 1.7.4.4/99153.

My machine is win7, his xp

ARMA2 is downloaded via different steam accounts on each machine

DAYZ is downloaded and updated by playsix

game is launched via playsix.

both machines are behind the same router and then to a cable modem.

I would think it was some weird firewall issue but that it worked until the 28th and still works on some servers.

Note again that as long as only one of us is logged in to a server everything is fine.

I did notice that there was an update to my data files in the expansion directory, though not the dayz directory on the 28th which may or may not be a coincidence.

Suggestions would be greatly appreciated,

tom