VPN disconnect then reconnect fails

I have a problem with a VPN server:

Win2k3 VPN running at home site.
I can connect to VPN from within the LAN w/ no problems. I can connect then disconnect from VPN from within the LAN with no problems. When outside the LAN i can only connect the first time, then if i disconnect and reconnect i get error 721. I’m very confused because i thought this might be a DHCP problem but this work from within the LAN… Anyone have any ideas