Clients get disconnected

I am running TS on Win2k with SP3. I have clients who
connect from the local LAN and via the internet. The
clients who connect via the internet will lose their
connection many times during an average day, while those
on the local LAN do not. Out internet connection is via a
flex T-1 with 768kbs bandwidth.

We only have 5 clients connecting over this connection.
At each of the client sites, they are connecting with via
a DSL line with 128kbs bandwidth. Each client is at a
seperate location.

Each of the clients are running an application on the
server and will get an error message that the connection
with the server has been lost.

Does anyone have any suggestions.