Big IP Edge Client windows 10 no connectivity with VPN - works on windows 7

Hi we are using Big IP Edge client for VPN connection. We validate with user creds, machine certificate check and antivrus check.

When connecting from a windows 7 machine all is well and works as expected.

When connecting form a windows 10 machine, the VPN connects (Access policy is passed A-OK) and it all seems ok (ip address assigned from correct lease pool etc) but I cannot connect to anything! I can see the traffic leaving the client (when I look at firewall logs the client is sending out the traffic to servers i am trying to RDP to for example) but it seems when the traffic is on its way back it doesn't properly get handled by the client (as if maybe its not getting decrypted by the edge client and sent on to application layer or something like that)

Now we are running 11.6 Hotfix 6 which is compatible with windows 10 but so far support haven't been much help. I provided them decrypted tcpdump from F5, wireshark from client, f5wininfo output but last update from support was to disable windows firewall which made no difference (I knew it wouldnt as all outbound traffic allowed anyway and VPN connection is all outbound) then they asked to check that machine has latest windows updates! (As if thats got anything to do with it)

This is causing much grief as we are about to rollout win 10 to the company but unless I can get VPN working its delaying rollout.

Anyone seen this before?

Any help would be greatly appreciated.