I looked it up on the Internet and said it was a windows firewall problem, but I added the source folder to the firewall and it didn't help, nor did I turn the firewall off. Only off the Internet to run fast. Writing code like this will be very troublesome, I would like to ask how to solve it.
This is a screenshot of putting the folder where the source code is in the trust area
It's the difference between being disconnected and being disconnected.