Enabling cookies in Safari for the Duo "Remember this device for 7 days" feature.
Duo has a feature called "Remember this device for 7 days". This allows a duo to remember the device a user is signing in with for a week, so they don't have to authenticate their account every time they sign in.
Click the "Safari" menu
Click the "Preferences" menu item
Click the "Privacy" option
"Prevent cross-site tracking" should NOT have a check mark (must be unchecked)
"Block all cookies" should NOT have a check mark (must be unchecked)
You may need to relaunch Safari or at least reload your page to use the new settings
From your home screen, go to Settings > Safari
Make sure "Block All Cookies" is unchecked
Make sure "Prevent cross-site tracking" is unchecked