Nextcloud Docker + Synology reverse proxy: HTTPS not recognized, CalDAV 405, redirect loop with overwriteprotocol

[wwe]

there are many issues I would proceed in following order

1. ensure your https://xxx.synology.me address works both internally and externally (with customs DNS, hosts file etc) - should be ok now per your last post
2. clean up reverse proxy config:

@AdOtjuh

• Nextcloud1: http://xxx.synology.me:80 → http://localhost:8080
• Nextcloud: https://xxx.synology.me:443 → http://localhost:8080

this might be an issue a service can not server two different variants (http and https) on the same port

I would only setup 1 https rule and configure http → https redirect (in the reverse proxy).

3. “too many redirects”

• you didn’t share f12 findings
• likely comes from bad reverse proxy config.. usually Nextcloud relies on HTTP_X_ headers and overwrite* settings are only a backup/hard-coded setting to let the system know it runs behind reverse proxy but can not detect it’s real config likely headers are missing or not trusted - review 101: reverse proxy also look for real-ip and follow my little cumbersome writeup Apache Docker behind reverse proxy

4. router config - I have no clue about Adguard but I know Pihole can do DHCP (likely not very easy with Docker). In my setup I did it other way round - I configure my internal DNS as upstream/provider DNS in my router. You have to try a bit to avoid DNS loops (internal DNS) but at the end it works without touching clients.