subscriber networks disrupting connection

Hi,
I have set up a WANwith two subscribers.For the last couple of days the connection in the subscriber networks have been going from very slow to not going at all. I changed one of the wireless modems but the problem persisted. I use Win XP on my server and smartbridge wireless modems. Can someone halp me please!! I also want to protect my gateway.

define the term WAN....

I don't mean the actual definition either, I would like to know what you mean by two subscribers.

this is kind of vauge...there are too many things that could be causing this problem. personally i dont think using XP is a good idea for the server, as for me it has run too slowly. have you tried testing just one of the "subscribers" at a time? do you have any logs?