unable to ping server behind ltm

@ mike can you elaborate.when we disable arp for vips on ltm using command "modify virtual-address any arp disabled", how is it going to effect icmp echo. Also i can see that you were facing this issue after upgrade from VE 10.2.4 to VE 11.5.1. you would have definitely tried to failover . there is when the problem would have started, if i am right. According to my knowledge, arp would have been disabled before the failover. when you tried to failover, BIG-IP virtual addresses sent gratuitous Address Resolution Protocol (ARP) messages after a failover event due to which BIG-IP virtual addresses that should not respond to ARP requests start receiving arp-traffic after failover.