The customer triggered NetScaler HA failover, in the new Primary node, Storefront(SF) service status show down with Monitor connection Timeout error.
If you configure StoreFront monitor in NetScaler and bind to StoreFront service, NetScaler will send monitor probes with NSIP as the source IP by default.
In NetScaler HA deployment, two NetScaler's NSIP will both need to be granted access to StoreFront server.