I had a whole post of how non GNAT / CGNAT works with Rings server you can read here:
https://rpug.pdc.ca/index.php/topic,781.msg6110.html#msg6110.
It slightly out of date now as all the port 80's are now port 4608, and the point of return failure in the last diagram might actually be at the ISP CGNAT router and not the ISP Edge router, but that depends on the protocol used between the two routers. That doesn't change the mechanism of the return failure, just where it happens.
Ken, to clear up some terminology what you need is a public IP address, not static. Static simply means the IP address doesn't change but that doesn't mean that the IP address is publicly routable as you are finding out. Study the second diagram (Private-Private-Public) in my post, the IP address assigned to your CPE and the IP address assigned to the ISP CGNAT router would both be static but the one assigned to you is not publicly routable.
Anyway, Metronet may or may not a provide public IP address for a fee (you'd have to ask them) but you need to ask yourself does the benefit outweigh the cost. If everything you do online bar RPA works without one then the cost/benefit ratio may not be there.
All that said, yes I have a solution that in in-house testing (just me) works. I'll be making a post later today/tonight.
- Tim
Edit: Forgot to add that on CGNAT the public IP address you see when you go to places like whatsmyip.com and the like is not actually you, it's the IP address of your ISP's CGNAT router and your sharing that address with potentially hundreds of your ISP's subscribers.
