M4300 24x24f Link Status or compatiblity issue

Hi,

I have a bit of strange issue with VMware ESXi and the M4300 series that I'm trying to track down.

Bare with me its a long story ...

Using a pair of stacked M4300-24X24F each ESXi host in the cluster is connected to both switches using brand new Cat6A cables using the 10GBase-T ports.

If an ESXi host is rebooted OR if a cable is disconnect the 'Network Uplink Redundancy Lost' is displayed correctly as an alarm against the host. In the event of a reboot, no cable was pulled physically (just firmware reset) and with the other test a cable was pulled for 20 seconds and then re-inserted. For both cases the alarm does not clear after the error condition has been corrected.

So far I have tried fully patching ESXi 6.7, vCenter, the QLogic FastLinq 10GbE/25GbE adapters driver and firmware and the M4300's up to Firmware 12.0.11.11 to no effect and the behaviour is identical.

I selected a host at random from the cluster (they all have this issue) and disconnected both host patch cables.

I then plugged a new uplink from one of the now spare switch ports on the Netgear into a spare 1GbE Extreme Networks Switch that I found lying around (bare configuration just trunk ports and VLANs) and finally connected the cables I had pulled from the Netgear connected host and plugged them into some configured ports on the Extreme switch.

If I now reboot the host that is connected to the Extreme switch there are no alarms on startup and the alarm correctly resets on cable pull test.

Nothing more than common commands on port config such as trunk mode, allowed VLANs etc.

Tried disabling STP or manually setting edgeport mode but no difference.

Any ideas?

TIA

Gaz