This is just extra info, I don't have an answer.

Googling "muxserver_listen bind(): Not owner" (in quotes) has literally no hits.

That's a bit too specific. muxserver_listen is a function of openssl. It's trying to bind a socket to a (specific or arbitrary) port so that it can accept incoming connections. bind, a system call, is returning an error that stringifies to "No Owner".

It sounds like some kind of permission issue, but I can't find any docs on it. You don't appear to be Linux since it doesn't seem to be able produce that error message:

$ perl -E'say $!=$_ for 0..65535' | grep -i owner
Owner died
[download]

Try finding out under what circumstances your system's bind can return "No owner". Try searching for "owner" in the your system's bind(2) man page.