I have a PHP site that is using $_GET to collect data and save them into a PHPMySQL database
Is this server run by a hosting company on the internet? Or is it your server on your localnet?
I have successfully created a "SimpleServer".
You need client code for this.
I haven't paid for full plan for my site, so I don't have a dedicated IP address.
Then you must use client code. If you are not a commercial account, chances are your ISP blocks port 80 requests from the internet.