How to receive notifications from a host on the same Wifi network?
I don't know if there's an "easy solution" – but one way I could think of involves two apps:


an SSH Server on the device (plus a corresponding client on the PC)
tasker


Sending a notification to your device could then work as follows:


write the notification text into a text file
by means of your SSH setup, copy that file to your Android device (have a specific directory there for "incoming notifications")
on the device, have setup Tasker to watch that directory on changes. Whenever a new file arrives, Tasker should


read the new file
use its content to create a notification
delete the file



I have never set this up myself, I just know that Tasker has this capabilities (and remember having read of people using such a setup). For details on Tasker, please see our tasker tag-wiki.