What follows below is what you DON'T want to see...
VMware provides a set of utilities for troubleshooting, both within the esxi host and through the RVC. Here is a short list.
1. The vsan.reapply_vsan_vmknic_config RVC utility to refresh networking settings
2. The tcpdump-uw -i vmk? udp port 23451 -v utility to verify multicast settings
3. The tcpdump-uw -i vmk? igmp utility