FIs zitadel behind nginx?
FIf yes checkout this guide https://zitadel.com/docs/self-hosting/manage/reverseproxy/nginx
You can either setup your environment for TLS mode disabled, TLS mode external or TLS mode enabled.
FHm the 400 looks odd, zitadel has stdout logs, can you check these?
FNot it just stdout by default
FWe ATM leave log collection to the infra layer, since you use docker you can send the logs to a log collector of choice. But I guess docker should have a copy as well in your filesystem