One cert to two servers?

I have now trying to setup a nethserver that going to work as Reverse Proxy to some of my webservers I have at home.

Before I did that I did use my ubuntu server that was running apache2 and did have letsencrypt that was was running manual. Everytime I did do that I did have to export the cert to my nethserver that was running Nextcloud so it was safe to run HTTPS.
I did take alot of work but was only idea I have to make it work. So both my ubuntu server and Nethserver with Nextcloud did use same cert.

My question is that possible if I know both running nethserver to make it easy for me?

or is that any better whay to make so Nextcloud (and also mailserver) running HTTPS.

The certificate of the reverseproxying Nethserver (Letsencrypt with autorenewal) is used so you don’t need a valid certificate on the Nextcloud server.
This way you don’t have to export certificates.
Don’t forget to add the domain names used for reverse proxies to the Letsencrypt certificate on the Nethserver.

If a webserver has no valid cert you need to “Accept invalid SSL certificate from target” in the reverse proxy settings: