DUO support ended for Internet Explorer 9 and 10
Starting in February, Duo is ending support for Internet Explorer 9 and 10.
Users will not be able to authenticate Duo prompts in Internet Explorer 9 and 10. Duo prompts will continue to function normally in Internet Explorer 11, Edge, or other modern browsers.
For more information please go to: https://help.duo.com/s/article/7620?language=en_US