Hello Pavan,
What are the specifics shown in the bottom-pane when selecting the 'Network Latency check', 'vSAN: Basic (unicast) connectivity check' and to a lesser extent the other checks? (e.g. stats for latency in ms between node 1 and 2) - (if you are using an older build of vSAN/vSphere that does not show these specifics, they can be determined from the health-service log on the vCSA)
If the Network connectivity between any nodes in the cluster is poor enough then pretty much all the alerts that are red here will be triggered.
Check traceroute between the vSAN interfaces on each node and also take a closer look at the stats of the vmkping between nodes e.g. not whether it passed or failed but more like did it take .1ms or 2000ms.
Check that the cluster is properly formed via esxcli vsan cluster get.
Bob