Lotus Notes from CISCO VPN client

Hi,
I have a strange situation. My mobile users logon without problems thru Cisco VPN Client (in an 1800 router), browse all the domain, access shared resources. Ping and nslookup to Domino Server are fine, too. But Notes reported Domino Server isn’t at right address. The DNS record is CNAME type and is AD integrated (Windows 2000 Server)
Login in site with same settings the same notebook work fine even with Lotus Notes/Domino.
Any Idea?