in this post I show docker config. You see there I use unencrypted connection to nextcloud app container (because going out of docker and returning back to the https interface of the reverse proxy didn’t work for some reason).
environment:
- PORT=7867
- NEXTCLOUD_URL=http://dev-nextcloud-app/ # NC app container name
if you access https (maybe because of http: >> https: redirection) you should configure notify_push app to use https:// The thread shows lot of different config examples and number references - most likely you find matching setup there… or you just add your router as trusted proxy…