I've been chasing this GUI problem for a few hours and finally gave up and went clui.
I've got four VMKernels all on their own VLAN / subnet.
Two are for NAS, one for iSCSI, and one for Vmotion.
Two ESX hosts, this is configured fine and working great. The third is my problem child.
Here's the output from esxcfg-vmknic -l
Interface Port Group IP Address Netmask Broadcast MAC Address MTU TSO MSS Enabled
vmk1 ISCSI SAN 192.168.200.69 255.255.255.0 192.168.200.255 00:50:56:63:52:62 1500 disabled true
VMkernelVLAN202 172.30.202.24 255.255.255.128 172.30.202.127 00:50:56:75:1f:38 0 0 false
VMkernelVLAN204 172.30.202.142 255.255.255.128 172.30.202.255 00:50:56:70:0d:7f 0 0 false
vmk0 VMotion 172.30.2.94 255.255.0.0 172.30.255.255 00:50:56:6f:78:99 1500 disabled true
As you can see two vmkernels are disabled and I can't enable them.
When I try to enable them
root@(severnamehere) root# esxcfg-vmknic -e VMkernelVLAN204
Error performing operation: SysinfoException: Node (VSI_NODE_net_tcpip_plumb) ; Status(bad0005)= Already exists; Message= Unable to Set
I've confirmed that the IP doesn't exist on the VLAN and even tried to add a second on that subnet. I was promptly chastized for trying to add another VMKernel to that subnet from the same host.
In the GUI, these all show as port groups.