MySQL Windows 10 Problem

I am having a problem with Windows 10 and MySQL 5.7. I am running Windows 10, PHP 7.0 and MySQL 5.7. This is a busy server with a high volume of transactions per second. It has been running for several months without issue. This problem, though, has become serious in just the past couple of weeks.

The error is as follows:

mysqli_real_connect(): (HY000/2002): Only one usage of each socket address (protocol/network address/port) is normally permitted.

The standard solution is to edit the Windows registry and increase the dynamic port range to 65,535. Another is to reduce the TIME_WAIT state to 30 seconds from the default of 240. I have done these and the results are confirmed via netstat.
Further, when I monitor the dynamic port use via netstat, it appears that far fewer than 65,535 dynamic ports are in use. On a typical query, fewer than 10% are in use. Reducing the load on the server by 50-75% does not seem to solve the problem.

So the problem is that MySQL/PHP/Windows are reporting socket exhaustion, yet there appears to be plenty of sockets.

PLEASE NOTE: I will not be able to let you login to MySQL either directly or via PHPMyAdmin or directly. Nor will I be able to provide any kind of remote access to the computer. We have to solve this via email, etc.