From the command line run:
>REG ADD "HKLM\SYSTEM\CurrentControlSet\Control\Class\{4D36E972-E325-11CE-BFC1-08002BE10318}\0007" /v "*JumboPacket" /d 9014 /f
Just check the ClassID is that of your vmxnet3 adapter by looking at the other registry values.
I searched for 'JumboPacket' in the registry and found it in multiple 'classes'. Does the record need to added to all of them?