Hey Tangy!
There's a lot of reasons why you might not be able to connect to each other on the same network. Usually the problem is with the network itself. For example corporate or school networks may prevent devices from finding each other.
Something to try might be to create a hotspot on your phone, connect your pc to the hotspot and try and message from there.
(Do note that usually wired connected devices and Wi-Fi connected devices don't go together very well...)
I hope you figure it out, let me know if you need anything! :)