Flash is a bug ridden POC that is not fit anything these days.
The sooner it goes away once and for all, the better.
Love him or loath him, Steve Jobs made a really good decision (IMHO) to not allow flash on iDevices.
To me, that started the death wane of flash. I signed up to a Photo printing service a few months ago. It needed Flash to upload my images. WTF moment. Deleted account 5 minutes later.
Your VPN is probably out of the arc but IT departments are loathe to change those sorts of things. More than their jobs worth.
So you will have to stick with IE until MS decides that they should junk it (please properly kill Silverlight at the same time).