You can see attached where I've defined the ports but obviously as you've said if I set a custom IP it ignores those. Possibly some sort of note indicating that when setting the network type to anything custom. It's difficult to show but when launching the WebUI from the docker page it uses the correct port instead of the ones I defined.
On a separate note, would it be possible to create a separate docker NAT for several other containers? Such that I want to setup a reverse proxy on 80 / 443 for several containers however I don't want to interfere with the unraid host UI running on 80 / 443. Basically have Unraid on 192.168.1.10 using 80/443 and then have a Traefik container on 192.168.1.20 on 80/443 and then have several containers not accessible from outside that Traefik will manage.