Citrix hogging the DSL Connection

I’m having a little trouble with a client where 3 Citrix users are connecting to main site via ADSL/VPN.

Sniffer capture shows full Enet header / 14 bytes payload. This is fine in the LAN, but these users are dying in the WAN. I’m not sure about the current rev, but are there some opinions as to how to tune the connections or upgrade to the most efficient version?