How to send a message from phone to computer?

Question

Android

Such a question is how to send a message from the phone (application on xamarin, android) to a computer, on the same Internet network.
I used these articles and the code from them, but nothing came of it, I'm sure that I'm doing something wrong.
https://metanit.com/sharp/net/4.1.php
https://metanit.com/sharp/net/4.2.php
Messaging between programs works on the same computer.
And tell me what to use tcp, udp, http in general?
In the future, you will need to send a photo from your phone to your computer.

Answer 1

start with ping
ping is the most reliable way to check if there is a network or not
with disabled firewall, Avast and other crap

Answer 2

the easiest way is to set up an http server on a computer and communicate with it, there you can also download files out of the box, but this solution loses in speed to others.
tcp / udp is a good solution, but you will need to implement your protocol for communication and configure the computer with the necessary ports for communication. You can also try the solution with websocket (protocol over tcp)