FW to FW connection drops between VMs in Vsphere

I have a vm network in vshpere with 2 DCs, they route through the fortigate 100e to a remote site with another 100e on older software. The DC1 can ping let’s call it IP 10.0.0.1 but DC2 can’t ping it. DC2 can ping 10.0.0.2 and DC1 can’t ping it. 
Both DCs in vsphere have exact same configs, on same host, same subnet. For the life of me I’ve been battling for months trying to figure out what it could be…. I need someone to help me deep dive and solve the ping drops that occur from other sites behind the remote fortigate….