Using AnyConnect client 3.1.05187 on Windows 2012 R2 (a Hyper-V VM), the VPN connection is established and all works well, but after 15-20 minutes, can no longer access the remote network, even though AnyConnect still shows as connected and no error alerts.
The Windows firewall is off, no other software besides a base Windows 2012 R2 install. The same connection worked fine on a Windows 7 VM (different physical host, ESXi).