403 forbidden - Cloudflare worker


I try to reverse proxy NodeBB forum from a Wordpress site. Both sites are hosted on different servers.

Site 1: Wordpress ( - WP Engine)
Site 2: NodeBB ( - Google Cloud)

DNS Setting for NodeBB forum is done via A record and it’s pointing to the IP Address of the Google Cloud VM Engine, and it’s grey-clouded.

I use Cloudflare worker to traffic to So far, everything looks good, I can see the forum. All the assets are loaded properly. However, apparently there’s an error with (403 forbidden).

Any ideas and suggestions?