Got a situation where a VPN connection is being sporadic in its routing. Its a Windows Server 2003 environment, and the server is handling both DHCP and RRAS. When I look in DHCP, not all of the handed out addresses are listed, and RRAS has the rest of them in its list. I can connect with a Windows 7 machine, and sometimes, I will have no Internet connectivity, and no access to internal resources, except for being able to ping and RDP into the server hosting RRAS. Ping fails on all addresses, so its not DNS. Other times, everything is fine. Is this because DHCP and RRAS are fighting with the address scope? Are not all scope options (DNS server, gateway, etc) being given to me all the time? How do I make DHCP give out, and display, all addresses regardless of how a node connects (VPN, wireless, wired LAN, etc). Any tips would be appreciated.
I had an identical experience, but we also had a 24-bit subnet mask on our LAN and were running out of IP addresses. RRAS grabs addresses from DHCP in blocks of 10, and I discovered that our DHCP server wasn't configured to check with DNS to ensure that addresses were truly available before handing them out....which was a problem in our address-starved environment. So sometimes, VPN clients would get LAN addresses that were really available (and would work perfectly), whereas sometimes they were already registered to another host in DNS (and so the VPN client would get exactly the behavior you described above.
I did two things at the same time -- moved our LAN to a 22-bit subnet mask to open our our available range of IP addresses, and configured my RRAS server to hand out addresses from a block I manually assigned to it (and excluded from the DHCP scope). These two changes immediately resolved the problem.