vpn and term serv over dsl BROKEN

[sigpop]

i use sprint fastconnect dsl service. i have a zyxel prestige 645M-Plus dsl modem. msft win2k op sys. cisco firewalls.

i can vpn to our server and get an assigned ip addr, but then want to term serv to a server on that network. it fails. works fine for others using dsl from other parts of the country and also worked fine when i was on cable modem.

i can, however, vpn and term serv to a different server at a different location.

any hints?