When running a container with a custom port, the Nginx configuration files contained in /etc/nginx/sites-enabled/ are not modified to reflect the new port.
docker run -d -p 8080:8080 -e PORT=8080 --name lemonldap-ng lemonldapng/lemonldap-ng
root@9860dc9a1af5:/# grep -i listen /etc/nginx/sites-enabled/portal-nginx.conf
listen 80;
listen [::]:80;
Files in /etc/nginx/sites-enabled-orig/ do have the right port set though
root@9860dc9a1af5:/# grep -i listen /etc/nginx/sites-enabled-orig/portal-nginx.conf
listen 8080;
listen [::]:80;