root@localhost:~# uptime
22:21:32 up 3139 days, 19:42, 1 user, load average: 0.00, 0.01, 0.05
root@localhost:~#Yes, that's right, some ISPs rotate IPv6 subnets, negating many things IPv6 was invented for in the first place.
Tailscale, Nebula or any of the automagical VPN solutions you can run yourself (like Innernet, https://github.com/tonarino/innernet) will probably negate the issue as long as you can reach some server with a static IP.
It's still not a great fix, of course, because DDNS still causes outages while intermediate servers wait for their TTLs to expire and caches to clear, which means your record could point to the wrong IP for at least one minute per switch. That's fine for a mail server, but not great for other applications that don't handle servers dropping from the network so we'll.
- Even old routers support at least noip.com and update the IP when it changes
- major DynDNS providers have a custom tool you can install, running in the background sending the current IP every minute or so
- every major registrar has a DNS API, which allows you to send IP updates in a simple CURL command and putting that command into crontab automates this as well.
The server software can run on any address as long as you don't hardcode the listening IP, just like any other web server. You'd need a way to have the URL point to the right server, of course, so DDNS or similar is a necessity if your server doesn't have a static public IP.
The desktop connections to the machines from Guacamole are tuples of { protocol configuration, hostname/IP, credentials}. If you specify the device Guacamole connects to by its IP and then that IP changes, the connection and configuration will break. You can probably work around that with some kind of dynamic DNS setting, or maybe local name resolution (LLMR and friends) if the machines are on a flat network.
TL;DR you don't need it, but it helps.