Goodcloud - Cannot create a site2site network

Technical Support for Routers VPN, DNS, Leaks
1

I have 2 Brume2's. 1 at home and 1 at vacation home
Both Routers have DDNS enabled and working. Both routers I can nslookup the DDNS name and resolve to the WAN IP's. Both routers show up as online in Goodcloud. Both routers have cable modems. My issue is I cannot create a site2site network in Goodcloud. In the Add Network screen I choose both routers, then assign a Network name, then Next. Here is where I get the message - No device can be used as the Main Node of Site to Site. I have a port forward set up on each router for port 51830 to each lan Router IP. 10.10.10.1 and 10.20.10.1. Both routers are running version 4.6.8

What am i doing wrong to set up Site2Site??

2

Is your ISP using CGNAT, which is often part of cable modems?

3

Check if the WAN of ISP router or GL router has the public IP (not CGNAT).
If the PPPoE in ISP router, please open the port forwarding 51830 in ISP router.