RAS problems

I have RAS set up on my Win NT server. When the users dial in to upload or download information, sometimes it connects fine and lets them do what they need and other times it connects but when they try to access the information it states “There has been no response from the server”.

The users then try again a few seconds later and it will work (sometimes). Other times they have to keep trying a few times.

Any suggestions? My users are getting a little annoyed.

Thanks
Angie