Cloudflare load Balance with reverse proxy

I want to load Balance over to Wan’s to my nextcloud instance.

Nextcloud - reverse proxy - wan 1 and wan 2 - cloudflare - domain.

For now I’m using just one wan and the reverse proxy with a subdomain. And I plan to get a second internet provider. Out going Connections shouldn’t be a problem but when I access my nextcloud from internet it gets tricky I think.

  1. Is cloudflare offering an extra certificate? For now I’m using nginx with let’s encrypt. The data should be encrypted before it leaves my network.

  2. How I get through my reverse proxy? I must add an extra sub domain for load balancing becouse my reverse proxy…I don’t won’t to open ports direktly. So that I can access via to my nextcloud via cloudflare and cloudflare points to and through my reverse proxy or am I wrong?

I am very confused about this and hope someone can help me to understand what I should do and what happens there