Can't connect to server on second device

Hi.
So I am new to jellyfin. Everything is set up and working.
Jellyfin is installed on Win 10 and an android device and it is working fine. Now the problem is, I install the app on a second phone (wife) but when I try to log in, a message is coming up saying can’t connect to the server. I am using the same details as what I am using on my phone’s app.

I have tried to use the IP:port details too but no joy.

Any help in the right direction will help…