Emby Connect can't reach server (connection works fine via direct domain/reverse proxy)

[smity3 0]

Server version: 4.10.0.18 (started on 4.10.0.17 but auto-updated overnight)
OS: Windows 11
Server Setup: Reverse proxy (Caddy) in front of Emby, HTTPS via Let's Encrypt (handled by Caddy), External domain set from Dynu, "Handled by reverse proxy" mode.
Internet Setup: ATT Fiber using IP Passthrough with DHCPS-Fixed IP allocated, open ports configured on router. Usually have Mullvad VPN on with relevant programs split-tunneled, but for all these tests Mullvad was disconnected to rule out any VPN shenanigans. 

Hello,

I recently set up a reverse proxy to handle SSL for my server. Got it working fine and tested internal and external connections which all worked using the Emby App, Emby Connect, and direct from the new domain I set up. However, I was doing some cleaning and deleting some old users successfully when suddenly on the next one I got an error: mediabrowser.common.extensions.remoteserviceunavailableexception. From then on I have been unable to connect to the server at all via Emby Connect or through any app. When trying to do so I can log in but then I just see the option of my server name, and when I click it it says: "Unable to reach server name. We're unable to connect to the selected server right now." I get the same result on app.emby.media connecting from a separate device not on my home network. No settings were changed between when I set up reverse proxy and when the error started. 

I can still connect directly through my new domain from an outside network and get through to the server and playback works fine. I've double-checked the reverse proxy, DNS, and certificates and all are in order. 

I tried going through the Connecting From Client Apps page, and added some firewall ports that weren't in there before (even though I could still connect from anywhere before those were added up until now), and did all the other steps but still am having no luck. I tried unlinking and relinking Emby Connect emails from the users too. Any thoughts on what I may have missed or why Emby Connect suddenly doesn't want to reach my server? Log file attached. Thanks!

embyserver.txt

[Abobader 3504]

Hello smity3,

** This is an auto reply **

Please wait for someone from staff support or our members to reply to you.

It's recommended to provide more info, as it explain in this thread:

Thank you.

Emby Team

[Luke 42718]

Hi, does your Emby server dashboard display the correct addresses that you want Emby apps to connect with?

[smity3 0]

Hi, yes my WAN access shows my Dynu domain and my Home access matches my router DHCPS-Fixed IP. 

[pwhodges 2075]

The server running on Windows, right?  If so, check whether the network connection is shown as public (wrong) or private (correct); the setting can change unexpectedly.

Paul

[smity3 0]

Hi Paul, yes the Windows network is and was set to private.

It's weird because the domain entry is working perfectly so I know it's possible to get into the server, it's just Emby Connect that won't work. Either through any app or app.emby.media on a browser. 

[Luke 42718]

have you setup emby connect for your users?

Emby Connect

[smity3 0]

Yes, most users have been exclusively using Emby Connect successfully up until this point (a few years now). The only thing that changed was that I set up the reverse proxy. Emby Connect was still working fine for a few hours after I switched to the reverse proxy but then randomly stopped connecting from anywhere while the domain still works. It will "log in" from Connect but not actually go into the server, just allow you to choose the icon for it and then say that the server is unable to be reached.