Private DSL to ATM connectivity problems

[tsweda]

I have a DSL line connected to an ATM switch inside a private network. There is a DHCP server, PDC and POP3/SMTP server located at another site that is connected to the same ATM switch via a t-1 Frame circuit. From the DSL site, using a Win98, PC I can get an IP from the DHCP server, log onto the domain and my logon script runs. However, using either a W2K or XP professional machine I can only get an IP from the DHCP server. No domain authentication. No logon script. And - here's the really strange part - I can only receive mail not send UNLESS I establish a Windows VPN connection to the PDC.

Help for anyone with suggestions will be greatly apprecated.