We use to F12 in IE9 or IE10 to set the IE to IE8 mode. Unfortunately IE11 F12 is totally an “alien” interface.
You need to enable the Compatibility View. For example, I have a troux application hitting the error Unsupported Browser.
Go to the gear and select Compatibility View settings.
Check the Display intranet sites in Compatibility View or add the Websites to the Compatibility View.
You should be able to view the page now.