Hey Dougie
We had the same problem with a couple of servers that were set up with vmxnet3. What worked for us as a fix is, before doing a svmotion, we shut down the vm, downloaded the vmx file. Took a copy of the original vmx file as a backup :)
Changed
ethernet1.addressType = "vpx" to
ethernet1.addressType = "static"
Plus edited following:
ethernet1.generatedAddressOffset = "10"
ethernet1.generatedAddress = "00:50:56:95:00:07"
replace with:
ethernet1.AddressOffset = "10"
ethernet1.Address = "00:50:56:95:00:07"
This seems to work for us now.
Why this happens is another question ...
Krist