Nginx and Pihole

Hi
I have nginx reverse proxy and pihole running on the same host.
Nginx is set up in docker on port 81 (443 for SSL) and, by using MACVLAN, it is assigned an ip in the same network as pihole.
Pihole is the standard configuration and is not running in docker.

When I set up a host in nginx (example.com:2000) and, in the Pi's DNS settings, direct example.com to the IP of the Nginx reverse proxy (as stated above, same network as pihole), it doesen't work. I get a 'Bad Gateway' error. When I try to connect to example.com:80 I land on the Nginx welcome page. Tried with several domain names and services and flushed cache every time.

Anyone got an idea what the problem might be?
Thank you!