Speed up NT 4.0 VPN?

Have installed NT 4.0 VPN using fast machines and high speed DSL. However, the functional speed is 9500 Baud, and stays the same with as many as 10 persons downloaing. It’s isn’t a CPU speed issue, but must be a registry controlled setting. HOW DOI SPEED IT UP? i HAVE SEEN THIS QUESTION ELSEWHERE, BY OTHERS, WITH NO RESPONSES. Please! My “check” ($) depends on it!
Thank you,
Tony Weiler,
tony@telemind.com