This is my code to connect on DataBase.
private MySqlConnection conn;
string connString = $"SERVER=12312321; PORT=3306; DATABASE=yyy; UID=yyy; PASSWORD=passs;";
conn = new MySqlConnection(connString);
conn.Open();
conn.Close();
Every two weeks I have a problem with our users from other countries. They cannot connect to database for 1-2 days, after that it works smoothly. Now problem raised again and I have used VPN, and using IP from my country works, and using IPs from Italy, Spain, Germany, US, etc got this error: Error: 0 : Unable to connect to any of the specified MySQL