From VMware support I was told to do this for one virtual NIC (vmnet1) but it did not make a difference on its own.
This is what I wrote back to VMware support
What did work was to move the Management Network to vmnet1 on the ESXi server. THEN the ESXi server could see the Openfiler iSCSI SAN.
When I restarted the management network, the Vcenter server couldn't connect to the ESXi server because the physical card connected to vmnet0 had disappeared!
Reconnecting the Physical NIC to vmnet0, it seems OK to connect VMs to the ESXi server but...why is this happening? It has to be a bug in either ESXi or Workstation for Linux.
What happens when I create another vmkernel port on another vmnic for vmotion? Will I have to move the Management network again? Will I lose connection to the Openfiler SAN if I do this?
I'll try changing all of them vmnet0,1,2,3 and see if this makes a difference. It appears to me at the moment that the VM will only communicate through the network which has the Management network for the ESXi host running on it.
I'll try a few more changes tomorrow to try and get a proper fix/workaround