I may have found an issue with 1.9.0. Creating a Virtual Machine Network with

apiVersion: <http://k8s.cni.cncf.io/v1|k8s.cni.cncf.io/v1>
kind: NetworkAttachmentDefinition
metadata:
  annotations:
    <http://network.harvesterhci.io/route|network.harvesterhci.io/route>: '{"mode":"auto","serverIPAddr":"","cidr":"","gateway":""}'
  name: vlan1
  namespace: default
spec:
  config: '{"cniVersion":"0.3.1","name":"vlan1","type":"bridge","bridge":"mgmt-br","promiscMode":true,"ipam":{}}'

Is causing an error

Error from server (InternalError): error when creating "STDIN": admission webhook "validator.harvester-system.harvester-network-webhook" denied the request: Internal error occurred: can't create nad default/vlan1 because nad MTU 9000 does not match cluster network MTU 1500

How do I set the MTU of the virtal network?