Cloudflare has a ton of services from filtered/unfiltered DNS to Tunnels/ZeroTrust.

but I set up the DNS thingy

From this, I guessed you were attempting to use just the DNS portion like 1.1.1.1 or 1.0.0.1. If I misunderstood, me skuzi. What I’m talking about is:

www.cloudflare.com/zero-trust/products/access/

The caveat to use Cloudflare Tunnels/ZeroTrust is that you need a proper domain with which you can change the nameservers. Duckdns.org or similar won’t do. When you sign up for ZeroTrust, they will give you two nameserver entries. You take those to your domain registrar and insert those in place of the registrar’s nameservers. I got a domain name from NamesCheap for less than $5 USD.

“I’m on my phone 100 miles away from home, open Jellyfin/Nextcloud/whatever

Cloudflare Tunnels/ZeroTrust will do that and more. They have all kinds of bells and whistles that are available on their free tier. I didn’t need most of them. It will do all of that without having to adjust your server’s firewall like UFW. You don’t have to worry about port forwarding or such on your router. It just punches a hole in all of that, and delivers what you need. No muss, no fuss.

To be fair, Cloudflare Tunnels/ZeroTrust is not unique. There are a plethora of ZeroTrust Tunnel providers. Ngrok comes to mind and seems to be the more popular of the alternatives, but there are others. Like I said previously, it took me a couple tries to get Cloudflare Tunnels/ZeroTrust down pat. Not so much that it was overly complicated, that’s just usually my modus operandi. I’m dense some days. LOL