VPN Setup in NT 4.0

Does anyone know of any special issues regarding VPN setup in NT4.0 that are not covered in the Microsoft whitpaers. I have downloaded the papers and followed all the steps as a client and yet cannot connect to a remote server that has been used by Windows 98 and 95 clients for over a year. RAM, ROM, and RAS are not the issues. Ports are configured. We’re using an Alta Vista firewall and punched a hole in it according to suggested number and guidelines