an attempt was made to access a socket in a way forbbiden by its access permissions. why?

Most likely the socket is held by some process. Use netstat -o to find which one.

Reload Visual Studio with Administrator privileges. Windows Sockets (WinSock) will not allow you to create a SocketType.RAW Socket without Local Admin. And remember that your Solution will need elevated privileges to run as expected!

Well I don't even understand the culprit of this problem. But in my case the problem is totally different. I've tried running netstat -o or netstat -ab, both show that there is not any app currently listening on port 62434 which is the one my app tries to listen on. So it's really confusing to me.

I just tried thinking of what I had made so that it stopped working (it did work before). Well then I thought of the Internet sharing I made on my Ethernet adapter with a private virtual LAN (using Hyper-v in Windows 10). I just needed to turn off the sharing and it worked just fine again.

Hope this helps someone else having the same issue. And of course if someone could explain this, please add more detail in your own answer or maybe as some comment to my answer.