Is this a new feature request?
Wanted change
I tried to make it work but seems to be incompatible atm.
in order to run on the gluetun network it's necessary to define ports in the gluetun section and then, in the other compose define something like:
Reason for change
Maybe it's enought to define a new variables WEB_UI, SYNC_PORT where store the ports using env instead of ports. But i'm pretty noob so i don't know if it's feasible.
Proposed code change
No response