If you Log on using dial up networking, from a Windows NT 4.0 server acting as a DUN client, the source IPX network corresponds to your local network. This causes the RAS/RRAS server to ignore your request.
To resolve this issue, you must change your local network ID to all zeros in the IPX/SPX Properties. This will cause your local server to use the IPX network number that it receives from the RAS/RRAS server as the source for the packet.
NOTE: This is only necessary when your DUN client is a Windows NT 4.0 server, using IPX/SPX as the