One remaining thing for today is replace gnudip.
Are you aware of #gnudip?
Chinese are!
Implementing RFC 2136 seems to be beyond their abilities so they dug this gnudip somehow and added to DynDNS options on some of their modern routers.
I found its source code on #sourceforge (yes, sourceforge! Remember that?), rewrote in Go, and happily used it for six months.
But now I have to say goodbye, gnudip. And not all routers support it, unfortunately.
Or it's better to go to bed?