Question : Problem: VPN : PPTP SERVER : Linksys WRT54G : Unable to browse or map drives from internal network shares

SETUP:
LINKSYS WRT54G
PPTP SERVER on ROUTER
CONNECTED TO PPTP SERVER ON ROUTER

PROBLEM:
1. Opened a new browser
2. Typed in my fileserver ip address (192.168.1.102)
3. Received the proper Windows Logon prompt.
4. Entered valid Administrator level credentials.
5. Received a listing of shares on the server indicating a successful logon.
6. Click on a share to drill down - or try to MAP a DRIVE.
7. ERROR - "Resource not available, or you don't have permissions."
Any ideas??
Thanks!
- Dasher

Answer : Problem: VPN : PPTP SERVER : Linksys WRT54G : Unable to browse or map drives from internal network shares

If even occasionally you can "drill down" it is probably not really permissions but actually caused by too high an MTU (Maximum Transmission Unit) size, especially if it is a lower than normal performance connection. It is recommended you change this on the connecting/client computer and when possible, it's local router. The easiest way to change the MTU on the client is using the DrTCP tool:
http://www.dslreports.com/drtcp
As for where to set it, if not using automatic, it has to be 1430 or less for VPN which uses PPTP. There are ways to test for the optimum size of the MTU such as:
http://www.dslreports.com/faq/5793
However, this is not accurate over a VPN due to additional overhead. The best bet is to set it to 1260, and if it improves the situation, gradually increase it.
A couple of related links:
http://www.dslreports.com/faq/7752
http://www.chicagotech.net/vpnissues/vpndorp1.htm

For the record the local and remote sites must use different subnets. You cannot use 192.168.1 x at both.