Hi,@Takeshi.Welcome to Microsoft Q&A.
Your connection string appears to have a couple of issues.
You could try the following string.
string conString = "Server=192.168.100.53;Port=3307;Database=test;Uid=root;Pwd=password;";
//or
string conString = "Server=192.168.100.53;Port=3307;Database=test;User ID=root;Password=password;";
Added Port=3307 to specify the port number. By default, MySQL/MariaDB uses port 3306, but if your MariaDB instance is configured to use port 3307, you need to specify it explicitly.
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