The error, Bad Gateway 502, is an HTTP status code that indicates one server on the internet received an invalid response from another server. The error is independent of a user's setup, meaning that users can see one in any browser, on any operating system, and on any device.
Troubleshooting
Press F5 or Ctrl+R on your keyboard.
Enter the URL again (https://handitaxcloud.handisoft.com.au)
Select the refresh/reload button if available.
Start a new browser session after closing all currently open browser windows.