(re)define Unifi captive portal sockets

I’m running Unifi on HAOS & had to remap the default ports, as there were conflicts on the host with other running containers/services.

In particular, I’m looking at the captive portals:
8880/tcp → 17880 - Used for HTTP portal redirection
8843/tcp → 17843 - Used for HTTPS portal redirection

In & of itself this is not an issue, but when a Captive Portal client tries to connect in order to authenticate/key in vouchers, it automatically redirects to the default socket provided by the app, i.e. https://$HAOS-hostname:8843 - which does not resolve properly (as that port is bound to another app/container).

According to the Unifi documentation, these defaults should be editable on the instance by editing the <unifi_base>/data/system.properties file, but it’s not clear intuitively clear where this is found on the HAOS host.

On a ‘normal’ POSIX system I would simply SSH into the host & edit the I would expect to find @ /var/lib/docker/volumes/htms_unifi/_data/data/system.properties, but in the case of the standard setup, that option is unavailable & I (safely) ssh into the separate sandboxed ssh container/addon.

What is the ‘sane’ way of achieving my desired outcome of editing the file in the container - any file, in this or any other app/container - without completely borking my host?