For anyone stumbling across this after battling with SWAG, 502 errors etc.
I appreciate this is an old thread, but with lots of conflicting info out there, the answer for my issues was in the documentation.
The resolver.conf file had generated before I'd set up the custom network.
https://docs.linuxserver.io/general/swag - Search this page for 502
502
This error means that nginx can't talk to the application. There is a few common reasons for this:
The application and SWAG is not on the same custom docker network
Further up we talk about how to set up Docker networking, however there are some other common traps
The container name does not match the application name.
Covered in the section for Understanding the proxy conf structure
You manually changed the port.
Also covered in the section for Understanding the proxy conf structure
The container originally ran with host networking, or the default bridge.
In most cases the contents of /config/nginx/resolver.conf; should be ...resolver 127.0.0.11 valid=30s;, if this is not the case, you can:
Delete it, and restart the container to have it regenerate
Manually set the content(we wont override it)
Hope this helps someone, if nothing else, it will help future me should I have to do this again!