Cannot Access Server from Home Network, but Cellular Works

[lakinreid]

Hey all, 

I've ran into the weirdest issue after setting up my Jellyfin server. I followed the Windows setup and network pages from Jellyfin to a T, and have my DuckDNS and Caddy proxy all set up. Everything works as it should, except I cannot connect to my server on any device which is connected to my home wifi. I can connect fine from Chrome on the PC which the Jellyfin server is being hosted on, but my other PC and both phones in the house refuse to connect when the wifi is on. I get "Server Offline?" and error code: NSURLErrorDomain when I pull up the app. The other odd thing is, if I turn of my wifi and utilize the cellular network, it will load my movies and shows with no issues.

Some thoughts for yall:

Do I need to add IP addresses to the "Lan Networks" or "Known Proxies" fields within the Networking tab in Jellyfin? At the moment they are blank.

Could this be a firewall issue of some sort?

Hoping someone can point me in the right direction, as I can't seem to find people who are having the same issue as I! Thanks in advance for reading!

[TheDreadPirate]

Is Caddy running on the same host as Jellyfin? On your devices are you using the DuckDNS address even when on LAN? If so, do you have NAT Loopback/hairpin enabled on your router?

[lakinreid]

Is Caddy running on the same host as Jellyfin?  On your devices are you using the DuckDNS address even when on LAN?  If so, do you have NAT Loopback/hairpin enabled on your router?

So caddy is indeed running on the same PC as Jellyfin.

I have been using the DuckDNS address to login on the LAN, should I be using a different address at the login screen?

And I don’t believe I do have Loopback/hairpin enabled. I’ll go investigate that in a bit!

[TheDreadPirate]

You do NOT need to set a known proxies address in your case. You can use your DuckDNS address on LAN but if you don't have NAT loopback the traffic will go out to the Internet and come back. With all the bandwidth and latency issues that entails. With NAT loopback the router will keep traffic local when the IP address of a domain name resolves to itself.