Ooma has worked so transparently for me that I forgot how I had things wired.
I have my Internet coming to a cable modem which goes to ooma which is connected to my router. So the actual external IP is obtained from Comcast by ooma.
I initially got a DDNS account and pointed it to the address my router showed, which of course I've now come to remember is the one provided by my ooma box.
I'm thinking what I needed to do is to modify my dyndns.org to point it to ooma's external IP. Then configure port forwarding in ooma. I added the correct port and the IP of router gets from ooma (172.27.35.143). My router already had port forwarding of the correct port to the correct local 192.x.x.x address.
When I ping my dyndns.org address, it correct resolves to my ooma box, but I'm not getting the traffic forwarded.
Basically, I'm looking to figure out how to use Dynamic DNS when ooma is in front of my router.
Your could call Ooma support and ask for help, or you could just give in and place your Ooma device behind your router.
Placing the Ooma device behind (on the LAN side of) the router is what I would do. I have my Ooma Telo behind my router, and it actually seems to function better. You could at least try it for a while.
Most people don’t have any problems with the Ooma device behind the router, but a few do. If you do have QoS problems with your Ooma device, post those problems on this forum and someone will help.
I was going to put the ooma behind the router tonight if I couldn't get it to work.