Hi you did not answer if you have tested with both RRCs on the same LAN ?
I have no problem to resolve your DDNS hostname with 8.8.8.8 DNS so your Control side router must do something wrongIf you now the IP of the Radio-RRC router you can temporarily use it as SIP-contact IP then no DNS is needed.I can see that the DDNS is updated a few days ago so that parts works but I can not browse the RRC at port 8000 so the portforwarding is not working properly or the ip has changed. Have you set port 8000 as TCP ?, and 13000,13001,13002 to UDP ?
Denis,If you haven't already, get a copy of my networking checklist. ...73,Mitch DJ0QN / K7DX