@dunlix either way, if you don't have a config.json, it starts the web installer:
Connection lost from website unless running in dev mode
Whenever I run my forums using the standard ./nodebb start, it pops up saying that nodebb cant connect. However, when I start the server in dev mode, the site connects just fine. I didn't see any errors in console or the log.
This sounds like https://github.com/NodeBB/NodeBB/issues/5472, take a look at that issue and make the suggested changes.