Windows 2000 terminal services

We have a main office running a windows 2000 server, and were connecting to this from a branch office using a windows vpn and terminal services through the internet. Everything was working ok until one day last week. Suddenly our windows 95 machines can no longer connect to the terminal server. The virtual private network connects fine, but when we try to connect to the terminal server, we get a message saying “The connection to the server has timed out. Try connecting to the Terminal Server again.” We also have a windows 2000 pro machine at the branch office that can connect just fine. Why are we suddenly having problems?