This may or may not be NodeBB related.

Google Search works fine, but if you type domain.com into the address bar of Google Chrome with trailing text, e.g., "domain.com test" directs to NodeBB's search plugin. The problem is that it's using domain.com:4567 (with the port).

All domain.com and domain.net traffic is redirected to https://domain.com using nginx.

Is Google, nginx, or NodeBB affixing the port to the URL?