[Docker] cannot access NC internally when using reverse proxy

The issue you are facing:

for the installation I have used these two containers and my domain.:

From external network (VPN, 4G) everything works fine in https.

when i try to connect to the IP or the hostname of the machine i get:

for https: 400 Bad Request
for http: 503 Service Temporarily Unavailable

if it helps:
Router is a MikroTik
Docker host is Ubuntu Server 18.04