There might be a paid way. At work we have our phone numbers tied into zoom which ties into calling other phone numbers. It is used as a backend switchboard. So you could have a zoom number as your signal number which routes to your landline. Maybe.

Deja DUP has auto validation also. But besides “backup” I think everyone suggests using ZFS that auto heals bit rot. And don’t trust unplugged SSDs, they can suffer bit rot quickly if stored in a hot location

Edit NVM, read up on it. Seems like you have to run PCP protocal on IP4 to bypass thr CGNAT issues.

You can use any open port and port forward at the router, or is CG NAT only 80

Just setup wireguard on your server, add masquerading and ip forwarding. That single wireguard in, will give you full access to your lan