1. Make sure your caps lock is not on. The login is caps sensitive! Make sure you're typing everything correctly.
2. Do not use the numpad! Use the numbers above the alphabet on your keyboard.
3. Does your username or password have any unusual symbols such as ?$!@*-_ ect.? This can mess things up for some people. Make a new account if you're having trouble with symbols. If you make a new one, please try to stick with a-z letters, nothing capitalized.
4. Make sure that your keyboard language is in English! It won't log you in unless you have a US keyboard setting.
Update: the only way I was able to login was by using data on my phone. But unfortunately I cannot connect to the server despite having the page open through mobile.
Is the mobile using the same router via wifi as the computer? Or using data? It should work if wifi through the same router, but not via data.