ITS is aware that some users are experiencing 504 errors when authenticating with Duo Push. This is a vendor issue, and Duo is working to resolve it.
Please use the "Text Message Passcode" option as a temporary workaround.
We also recommend setting up Microsoft Authenticator as an additional authentication option. Please refer to our knowledge base article, How Do I Use Microsoft Authenticator for Two-Factor Authentication (2FA)?, for setup instructions.