Intermittent Connection Problem Between Active/Stanby LTM 1600 and a pair of Cisco 2960

I have a pair of LTM 1600 (namely LTM-A & LTM-B) running in active/standby mode and a two pair of Cisco2960 (namely WAN-2960-A, WAN-2960-B, LAN-2960-A & LAN-2960-B). My setup is as below:-     Ne...