Activesync Pass Through on network using a cache

[Guest Happy Dave]

Looking for some help please. At home all of this works fine so no issues there. However at work when connected via USB I cannot use the internet pass through on Activesync. I think its because we use a cache for all IE activity, e.g http://cachedomain.co.uk

Strangely I can collect email through the device, its all activity such as pocket IE, RSS readers, SPPB Weather that wont connect.

Anyone any ideas on how I can get round this? I use a HTC Wizard, WM5

cheers

Dave