esx.problem.vsan.net.redundancy.lost
Summary
VSAN network configuration doesn't have any redundancy. This may be a problem if further network configuration is removed.
Causes
One of the network interfaces used for the Virtual SAN network was removed, failed or is inaccessible.
Resolutions
Refer to this VMware KB article for troubleshooting steps.
External
Refer to the VMware Online Documentation for more information on vCenter event messages and possible solutions.