Ok, as it is running as a container the QUIC tooltip has no effect, as it is using 28967 internally anyway.
While installing the app the “Node Port for Storj” in the networking section is the point where you have to tell truenas which port you actually want to use externally for it to reroute.
For Example if you use 20988 ( I dont’t know why they chose this one)
outside world => 20988 => router => 20988=> node machine => 20988 [“Node Port for Storj”] => docker container => 28967 storj app inside container and which is reported on tooltip
You may also just use 28967 if it is not used elsewehere.
And how did you test the port is open?
EDIT: QUIC was working, now not - a few booboo's on the way - #4 by aardvarkl