Pihole v6 not loaded prioperly using hostname

[helpfinder]

Until now (with v5) I was using Nginx proxy manager and Pihole loaded via my local hostname (pihole.domain.com) > it was working properly.
After I updated to v6 it does not work with hostname, but it works with IP. Strange is a way how it does not work
This is how I see my docker Pihole when accessing it via IP

This is how I see my docker Pihole when accessing it via local hostname

Any idea why is this happenig and how to fix it?
Thanks

[yubiuser]

Are there any errors in the developer console (F12) of the browser?

[btb68]

You may not need to specify the path /admin in the proxy config. This was the fix for similar issue with cloudflared tunnel access on v6.

[ohshazbot]

No errors in the console, but the GET for auth returns a 401 when using hostname, 200 when using IP

[helpfinder]

If I do not use /admin in proxy config then I just recieve error

[helpfinder]

maybe this?