A few months ago, we commissioned a new VxRail cluster for our VDI workload. Installation and setup went without a hitch.
However, all hosts in vCenter displayed a High pNIC Error. This kept returning even after an error reset.

It was also strange that the specified adapters were not actively configured for VSAN at all.

After some back and forth at the hotlines of VMware and DELL we found the following error. The Intel network cards have a problem in connection with Cisco switches that header data are sometimes sent with different lengths.

If the Intel card receives such header with different length, it passes this “error” to the driver. Since vCenter 7.0 U2 these errors are also displayed in the vSphere Client.

Unfortunately, neither Cisco nor Intel has a solution to this “problem” and VMware cannot suppress this error either.

Solution was to exchange the Intel cards against Broadcom. Since then we have not received any High pNIC Errors.