How to configure Umbrel BTCPay Server with NGINX reverse proxy

I’ve tried this so many times and I can’t get it to work.
First, I was stuck on step 6. I was always giving an error “unauthorized”.
Then I managed to install a certificate (following this How to configure Umbrel LNbits app without Tor). Then I continued the steps.

Everything seems to be “fine”.
I can even access Umbrel and BTCPay throug http, but when I try HTTPS nothing loads and I get a “ERR_CONNECTION_REFUSED”.

I don’t know what else to do! Any ideas?