Hello SanyaAnishchik-6350,
Thank you for your question and for getting in touch.
Here's a suggestion on how to fix and make this type of connection:
In your desktop app, you can use an object of the HttpListener class: https://learn.microsoft.com/en-us/dotnet/api/system.net.httplistener?redirectedfrom=MSDN&view=net-5.0 and in your app mobile, you can call the url (using a web client object) from your desktop app. At the bottom of the link page you can find an example of HttpListener.
In the link mentioned above you will find an example of how to use HttpListener.
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