Settings for Nginx reverse Proxy in front of Nginx/Nextcloud installation

Hi I currently have a running and working installation of Nextcloud(18.3) and nginx running within a FreeBSD jail within a FreeNAS installation 11.3U3.

Additionally I have another Arch Linux VM running on FreeNas running nginx as a reverse proxy for my LAN.

I’ve yet to “link” the nginx reverse proxy and Nextcloud/nginx installation. I additionally use Cloudflare for my DNS records.

My question is regarding how to configure the reverse proxy to “proxy pass” to the upstream Nextcloud/nginx installation. What headers do I need to pass from the nginx reverse proxy to nginx nextcloud (if any)? I’m fairly familiar with working with SSL certs, and my intention is to terminate the SSL at the reverse proxy but then re-encrypt to the nginx/nextcloud upstream installation. I have LE certs which are different for both the reverse proxy and nginx/nextcloud installation – I don’t think I need any help on configuration of the SSL certs – only to the extent if they change the headers that might need to be passed.

Additionally since I’m using CF, I’m aware CF is also a “proxy” and I’m not sure if this changes anything with my installation as well.

Thanks.