Hi,
Please go to Windows Service manager, run "services.msc", then Look for the Remote Access Auto Connection Manager and Remote Access Connection Manager to see if those two services have been started. If not, set them to automatic start, reboot the machine,
and install\configure NetExtender again.
Since this is a third party application, it's recommended to contact the application vender to check the compatibility with Windows 8.1\IE 11, because they're more familiar with the application.
http://help.mysonicwall.com/sw/eng/2605/ui2/1000/Admin/SSL-VPN_2000_1.0_Admin-8-1.html
NOTE
This response contains a reference to a third party World Wide Web site. Microsoft
is providing this information as a convenience to you. Microsoft does not control these sites and has not
tested any software or information found on these sites.