I have a server that has a webserver and ssh server running.
Here is my setup with IP addresses:
Internal Network = 192.168.2.x
I have Ooma dmz set to 172.27.35.33 and vonage dmz set to 192.168.15.2
Everything worked fine before I inserted the ooma device. Does the dmz work on the ooma device?
Some people have Ooma Quality of Service problems with the Ooma device connected behind the router, but most don't.
If you do have QoS problems, post the problems and someone will give instructions how make corrections.
If you don't have enough LAN ports in your router, you can purchase and install a good "Switch" which will mulitply your ports.
I did this because I wanted the hub to be on its own, and I did want my network going through a device I did not know that well. Since I have a fast Internet connection, I was not too worried about QoS and the hub's ability to throttle my network's access to the Internet.
With ooma side-by-side with the rest of my network, I have no problems. It sounds like this might be a good option for you too, since you have a network a tad more complex than most.
Premier Service (I was not expecting to do this, but I love the Premier features)
Panasonic KX-TG4024 (w/ 4 handsets)
Customer since November 2010
Internet access: FiOS 15/5