w9amt I have Verizon for my cell and Metronet at home, both use CGNAT. I cannot believe there isnt a fix for this on the Shark RF end.
This isn't something that Shark RF, or any other Echolink client developer, is able to fix.
The problem is that Echolink was not designed to work with NAT. It was designed and implemented in the days when people only had a single computer in their home, so there was no need for NAT.
Echolink requires that UDP ports 5198 and 5199 on the outside (the public IP, as seen by the other party you're trying to communicate with), map to ports 5198 and 5199 on the inside device (computer, phone, tablet, M1KE, etc.). Unless your router has more than one public IP (the IP seen by the outside world, which is not 10.x.x.x, 100.(64-127).x.x, 172.(16-31).x.x, or 192.168.x.x) on its outside interface, it only has one UDP port 5198/5199 available, which means it can only map each of those ports to a single internal device.
This is why Echolink doesn't allow more than one client within the same network. It was designed to use only those particular port numbers, there is no way to make it use any other port numbers - at least not if you want it to work with the current servers - and if it doesn't talk to the Echolink servers, it isn't Echolink anymore.
This was a "less than ideal" design decision made in (or before) 2002, back in the days when cable modems were just starting to replace DSL lines as the "high speed internet" option for consumers. Most people didn't have more than one internet-capable device in their homes back then, so there was no need for NAT. (I was building and running dialup ISPs back then, I did this stuff for a living. I had to physically build a Linux machine with two ethernet cards and configure the firewall rules to do NAT by hand in order to have more than one working computer at home.)
It would be nice if Echolink's documentation explained this more clearly, but ... I guess nobody wants to admit that Echolink's basic design is broken, and the only way to fix it would be to replace it with something better.
