F5 not forwarding traffic to Pool Member - Cookie issue ?

I have setup like below:

 

Client -> (Internet - Public IP Web portal) -> Firewall/ NATing local IP - > LTM1600-VIP-1 -> Pool-Members (Middle Servers) -> LTM1600-VIP-2 -> Pool-Members (Web Servers) both http and https traffic and URL uses cookies.

 

when no issues... then no issues.

 

but when user complaints for web portal not working then below observers (neither http nor https works).

 

first page (it is simple two line welcome page) always opens from Client LAPTOP.

 

but issues > first page contains two link, and sometimes first link on click does not load contents and some times other link when click does not load contents .... and page only displays loading (circle -round - round symbol).

 

NOTE > both VIP-1 & VIP-2 are on same hardware (LTM1600 + 11.4.1) box but on different VIP, different subnet & Source Address Translation is Auto MAP and default configuration by iApp.

 

NOTE > when we open the same pages (curl) from Middle Servers, we get response, means working.

 

NOTE > when we open the same pages (curl) from LTM1600-VIP-1, we get response, means working.

 

took tcpdump at LTM-VIP-1, and found that Client traffic is very much reaching to F5-LTM

 

what could be the issue , why F5-LTM-VIP-1 not forwarding the traffic to other side.

 

NEERAJ JAGETIA