Oh it does. But. (and this is a big but).
This is the default:
It'll start fine with the defaults on install. (1880, 18443).
Now, if I change http/https to 80/443, it barfs. Because Unraid itself is already using those. It would be fine to live on the default ports, if I was using IPv4 only.
The problem lies with ipv6. Because you don't forward ipv6 ports (at least I don't, native /56 network to play with).. then https (v6) = 18443, not the expected 443. There's no network translation, therefore no port forwarding. Therefore having ipv6 on anything *other* than 80/443 isn't an option.
So, the way to get around that, is use something other than bridge. But the config won't do custom ports that way. It forces me to use the defined ports only. So I'm back to square 1. Can't use v6 with the docker.