Can't connect android devices on local network to server. Other devices can connect.

[aqwertyuiop]

Hello,

I've just finished setting up Jellyfin server on my desktop PC.
I can successfully connect to the server via localhost, and also from my laptop using the IP address of the host device.
However, I am unable to access the server from my android phone (via the play store app), or through my chromecast (via the android google TV app.) All devices are connected to the same WiFi network.

I am trying to figure out if there is an issue in the android network settings, some kind of firewall issue or something else (router settings?)
I unfortunately have no access or control over the router in my current living situation, so I am hoping it is not a router issue.
(Although to me it seems that if there were a router settings issue, then I would not even be able to connect from my laptop.)

Is there some weird setting on android devices that I don't know about that is blocking me?
Is there some windows firewall setting that would only apply to my android devices?

I've also tried setting up hotspot on the phone, and running the server through that, but I still can't connect.

Any help appreciated.

Thanks.