The vCenter Server and DNS server are initially deployed to the services host. After the vSAN stretched cluster is built, these server VMs are migrated to the vSAN cluster using vMotion. This requires a VMkernel adapter with vMotion services enabled. The vMotion VMkernel adapter and its connected vSwitch are also configured to support jumbo frames, meaning the MTU must be set to 9000 bytes. This provides the best performance and is required for the vCenter health checks to pass.
These settings are done as follows: