Help w/VOIP gateway using Linksys router!

Anyone out there have experience with the Linksys BEFSX41 Firewall Router with 4 Port Switch/VPN?

I have 3 computers (2 WinXP PC’s and one Mac running OS 8.6), and a DTA 310 VOIP gateway. I work for an ISP and we’re thinking of trying to sell VOIP and so I’m the guinea pig, equipment wise.

But. When I plug in the VOIP gateway to the router, the connection goes up and down. I originally had it plugged into the 4th port, which is the DMZ port, if you enable DMZ. So I figured that was the problem.

DMZ was disabled, so port 4 should be just a regular LAN port… but the router loses synch with the modem when the VOIP gateway is plugged into port 4. It’ll come back up, then lose the connex again, over and over.

So, I switched things around. I enabled DMZ, set my machine ( as the DMZ host and plugged it into the DMZ port, port 4. Then I plugged the VOIP gateway into port 3, my roommate’s computer into port 2, and the Mac into port 1.

Same thing. Router loses synch every couple minutes.

I unplugged the VOIP and the connection seems stable. So I disabled DMZ, and plugged my machine into port 1, Jim’s into port 2, the VOIP into port 3.

Again, router loses synch repeatedly.

From deductive reasoning, it looks like it’s the VOIP gateway that’s the problem. With it plugged in, the router keeps losing synch with the cable modem, no matter what is plugged into what port. Could it be that the VOIP gateway is like… “overloading” the router? There’s a LOT of activity when I have it plugged in; I think the VOIP gatway makes too much traffic or something, because when I remove it from the equation, everything works, even with my machine plugged into the DMZ port. (With DMZ enabled or disabled.)

This is all kind of vague, but I figured I’d throw it out there for some feedback. Thanks in advance!