Nextcloud host with nginx

[Komba]

Hey guys
there will be a tl;dr on the bottom. I used this Nextcloud QPKG https://www.qnapclub.eu/pl/qpkg/348 for a while now but just noticed that major version updates (in my case 20.x to 21.x) are not supported. A nice guy from Reddit told me that I could use a NC containerstation from linuxserver.io instead and so I did. It works fine if I use my local QNAP IP with the portnumber behind it but I want it to be accessible from outside this network just like the old NextCloud I had, for that I use the
jlesage/nginx-proxy-manager container which worked fine. So I shut down the old NC, start up the container one (same IP, same port, same DNS configured in nginx, worked with old one so it should work with the new one too) but the site (https://example.dns) now is loading for ages until giving me an openresty 502 Gateway Time out Error.
TL;DR
Had this NextCloud https://www.qnapclub.eu/pl/qpkg/348 but major updates are not supported.
Now tried this ghcr.io/linuxserver/nextcloud in container station.
Works inside private network but not with DNS which is configured in nginx.
Nginx configuration of that proxy host worked before, should work now too as the new nextcloud works on same IP and same Port.
It doesnt.

Anybody got an idea where I am wrong?

[Rello]

There is the more or less official docker NC.
Running within 1 minute almost.
did you try this?

at the end it should only be a topic of assigning a fixed IP and then doing a port forward in your router/fritzbox. I don´t see the issue