I can’t give too many details just now and I’m sure someone will offer more concise help but I used the details here https://docs.organizr.app/books/setup-features/page/serverauth
Any attempt to access https://sonarr.mydomain.com is redirected to a 401 page but it’s still accessible through Organizr.
This is through Nginx-proxy-manager but I’m sure the instructions will be almost identical.
I’ll be able to post more details of the setup later.