I am using ISA 2006 on the server side and the Windows Client VPN on the client side for my VPN access.
Everything works, but when accessing internal network resources over the VPN it is very slow when using the server names, however when using the IP addresses of those same resources the access speed is fine.
It's more than likely an issue with the name resolution over the VPN but I am unable to find the solution.
Server shares over the VPN:
If I access \\server_name\share the access is very slow.
If I access \\ip_address\share the access is much faster.
Web apps over the VPN:
If I access http://server_name/intranet
the access is very slow, 40 seconds to open the intranet home page.
If I access http://ip_address/intranet
the access is fast, 4 seconds to open the same intranet home page.
I have tried using different clients to connect, XP and 7, I have tried using different servers as the ISA Server, I have tried allowing everything through the ISA Firewall, I have tried using PPTP instead of L2TP, etc - however nothing changes this, if I access internal resources by name it is slow, but by IP it is fast.
I have checked that the details I get fromt he DHCP server when connecting via VPN and compared these to the details I get when connecting locally and they are the same - the same IP range, DNS servers, WINS server, gateway, etc.