I found the same problem in a camera project
I had Balena dashboard configure my OS file for my Raspberri Pi Zero W with CUPS and downloaded it . However when starting Public Device URL I got the error message
error when reaching this balena.io device: XXXnumber hiddenXXX tunneling socket could not be established: 500 possible reason is because nothing is listening on port 80 on the device…
I ran a check on the dashboard all is ok.
Nothing in the log either.
Can I check the port in terminal and change it? And how?
(I’m a noob)
I found some commands to work with (amazing google) and put it in terminal
netstat -lnt | grep LISTEN | awk ‘{ print ( 4 ) }' | awk 'BEGIN{FS=":"} { print (NF) }’ | sort -n | uniq
and Balena returned:
53
22222
48484
So no 80 indeed. Now I only have to know how to force it to listen on 80
The solutions I found in the forums go all way beyond my skills, and using 80 is not a very safe resolution anyway. So before going on, I will first try to setup another solution for pi/airprint outside Balena OS. Maybe I’ll be back.
Best, Ruud