@julian I found this: https://github.com/NodeBB/NodeBB/issues/4734
Using the certbot configuration, I edited /etc/nginx/sites-available/default
Leaving the certbot managed parts as they are, my custom config looks like this now:
proxy_set_header X-Forwarded-Proto $scheme; location / { proxy_pass http://127.0.0.1:4567; }The special part is the x-forwarded-proto line, that's what I was needing all along.
And in /home/nodebb/nodebb/config.json I'm setting the URL with https:
{ "url": "https://forums.mydomain.com", "secret": "<REDACTED>", "database": "mongo", "port": "4567", "mongo": { "host": "127.0.0.1", "port": "27017", "username": "nodebb", "password": "<REDACTED>", "database": "nodebb", "uri": "" } }This resolved my problem.