Points of My Scenario:
1. I have 3 ESXi standalone servers (A, B, and C) identically configured and connected to physical network.
2. The vswitch0 for each ESXi server is connected to 2 physical NICs.
3. The switch ports connecting all ESXi servers are trunked to the same VLANs 1, 2, 3, and 4.
4. I have test VMs running on each ESXi server.
5. Whenever I configure the VMs onto VLANs 1, 2, and 3 portgroups - they are all able to communicate with each other.
6. Whenever I configure VMs onto VLAN 4 portgroup, only VMs on ESXi servers A and C can communicate.
7. I have removed and re-added VLAN 4 to ESXi server B using the web UI and CLI (and rebooted after each removal/re-add): still no success.
8. HOWEVER, when I configure ESXi server B's management portgroup to VLAN4, this physical ESXi B server is able to ping VMs on ESXi A and ESXi C - and, VMs on ESXi A and ESXi C can ping the physical ESXi B: proving VLAN4 is working on the physical ports used by ESXi B.
9. I have also executed "Reset System Configuration" under "System Customization" at the DCUI, then re-configured and performed testing as above (getting same results).
QUESTION: What else can I troubleshoot to figure out why the VLAN 4 portgroup on ESXi B won't work.