Unable to connect to any of the specified mysql hosts. C# MySQL

Sometimes spacing and Order of parameters in connection string matters (based on personal experience and a long night :S)

So stick to the standard format here

Server=myServerAddress; Port=1234; Database=myDataBase; Uid=myUsername; Pwd=myPassword;

I am running mysql on a computer on a local network. MySQL Workbench could connect to that server, but not my c# code. I solved my issue by disconnecting from a vpn client that was running.

Since this is the top result on Google:

If your connection works initially, but you begin seeing this error after many successful connections, it may be this issue.

In summary: if you open and close a connection, Windows reserves the TCP port for future use for some stupid reason. After doing this many times, it runs out of available ports.

The article gives a registry hack to fix the issue...

Here are my registry settings on XP/2003:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\MaxUserPort 0xFFFF (DWORD)HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\MaxUserPort\TcpTimedWaitDelay 60 (DWORD)

You need to create them. By default they don't exists.

On Vista/2008 you can use netsh to change it to something like:

netsh int ipv4 set dynamicport tcp start=10000 num=50000

...but the real solution is to use connection pooling, so that "opening" a connection really reuses an existing connection. Most frameworks do this automatically, but in my case the application was handling connections manually for some reason.