SCO

I have run across an issue with the last two Dell Poweredge servers I have attempted to deploy. I seems that when a telnet session sits idle for 5 to 30 minutes (seems random) the session is being closed and users are logged off. If the session has user activity there is no problem staying connected. I know it sounds like an inactivity timer but the odd thing is that this does not happen when connected via a local switch or crossover cable only through a router plus the idle out time is not consistent. VPN or straight telnet have the same result. I have flashed the router twice. Replaced the router. Installed an out board intel pro 100 nic (which is native to SCO). Locked the nic into 100mb fdx & adjusted the mtu from 1500 to 1300 ( per sonicwall tech support). Flown 1500 miles to do a bare metal re-installation of the OS. Replaced the machine. Remove all of the routers from the loop and connected the server direct to the internet. Moved the whole setup to a new facility on a different backbone in a different city. Still the issue remains. The kicker is that if I put a humble Power Edge 1800 non raid system on 5.0.7 MP4 with onboard Intel pro / 1000's it stays connected just fine. Has anyone else seen this odd behavior with this class of server or OS version?

The current configuration is:
Server:
Dell poweredge 2800 raid 5 perc 4/di ( amird )
Dual Procs, 8 gb ram
Dual integrated Intel Pro / 1000 using driver version 5.0.7f
SCO 5.0.7 MP5 (Updated from MP4)

Previous configuration:
Dell poweredge 6800 raid 5 perc 4/di ( amird )
Dual Procs, 8 gb ram
Dual integrated Broadcom BCM57xx / 1000 using driver version 9.4.1
SCO 5.0.7 MP4

Router:
Sonicwall 4060 on OS 3.2 enhanced

Alternate router used in trouble shooting process:
Sonicwall 3060 on OS 3.2 enhanced