

Please don’t apologise, you and the other commenters have been a massive help :)
It’s sod’s law though, I was supposed to have two pretty much free days yesterday and today, and they’ve turned out to be two of the busiest days I’ve had for a long time. Networking is one of my blind spots, I can never quite get my head around it, so gave myself two days to try to get up to speed and seem to have jinxed myself :D
I’m going to spend an hour or two now playing around with Cloudflare and Navidrome and see if I can get a better grip on it all.
Thanks again for the help :)

Sorry, I didn’t get a notification for your reply until this morning.
Thanks for the offer, I’d be happy for any notes or advice :)
I managed to get Navidrome and Immich set up last night through subdomains, like music.domain.com and photos.domain.com, using the existing Cloudflare tunnel. They seem to be working properly, but I’m going to check them when I’m out later to make sure that nothing was cached rather than being served live.
One thing I want to look at in the future is local domain names, so music.local etc. and possibly set up certificates to get rid of any warnings about insecure sites. I might switch from AdGuard to PiHole to help with that.
Something that might make you laugh, I got stuck for an hour or so last night trying to connect to Navidrome through the domain name. I could get to the login page, but couldn’t get it to accept my credentials. Substreamer wouldn’t log in either. I looked through pages and pages of search results, forum posts, and manuals, but couldn’t find an answer. Just before I gave up, I copied the address from Firefox to try in another browser, and realised that I’d forgotten the s in https 😫