Hi Steve,
Is the problem with web access or fileshares? Have you been able to capture a tcpdump of a failure? It sounds like there might be some kind of look up being performed on the servers which times out. I've done a few Sharepoint implementations for customers and not seen this issue. We typically use standard VIPs with client SSL, HTTP, OneConnect with a mask of 255.255.255.255, and cookie insert persistence set to ~30min.
The deployment guide doesn't cover fileshare access. To allow it, you'd need to configure a VIP on port 445 with a TCP profile. This post might also have some related info for fileshare access delays (
Click here).
I'm surprised that F5 Support wasn't able to help you resolve this issue. What was the result of the case?
For point 2, do you have a persistence profile added to the VIP? Can you try source address to start with and then move to something more complicated if that fixes it?
Aaron