Configure Nextcloud & Onlyoffice behind a DSM synology reverse proxy


I unable to enable onlyoffice with nextcloud behind a dsm synology reverse proxy.
The dsm proxy is used as SSL provider and frontend. Private traffic is therefore in http

My (dsm synology) reverse proxy (IP1 private, assign requests to 2 machines.

Nextcloud give me the following warning : “you are behind a reverse-proxy and the rewrite variables are not set correctly.”

I don’t know if i have to set header in the proxy, and what i should put in nextcloud config.php.

In DSM proxy you can personalized headers relative to each redirection.
I imagine that and are concerned
I think that i have some inputs to do like

Upgrade $http_upgrade;

Connection $proxy_connection;
X-Forwarded-Host $the_host;
X-Forwarded-Proto $the_scheme;
X-Forwarded-For $proxy_add_x_forwarded_for;

Anyone can help me ? thanks