I don't think there is a SOL for it in the wild, but you need to turn off hardware SYN cookie protection for network virtual servers. It doesn't behave properly when turned on for anything other than a /32 destination virtual server. We had many problems with this last year and our local FSE finally confirmed it and sent out a newsletter detailing that it should be turned off. Software SYN cookie protection should get you by for those network VIPs. If not, contact your local F5 team. As soon as you disable hadrware SYN cookie in the TCP/FastL4 profile attached to the VS you should see things get better.