Is server #3 loading DHCPCLNT.NLM? Type 'm dhcp*' at the console to see if it's loaded, and check AUTOEXEC.NCF for a command that loads
If yes, then that is why it's IP address is changing.

If no, then this remains a mystery, in which case it might help if you

were to export the following...

1. DHCP Subnet
2. DNS Forward Lookup zone (RLMINT.COM)
3. DNS Reverse Lookup zone (should be

...then copy/paste the contents of each into a reply here.

NSC Volunteer SysOp