An on-premises network has been extended to azure with a VPN/ExpressRoute.

Network Security Groups (NSGs):NSGs control the inbound and outbound traffic to and from Azure resources. For traffic between on-premises CVMs and NC2 CVMs in Azure, the NSGs associated with the Flow Gateway VM's Internal NICs must be configured to allow the required traffic.

Editing NSGs:To enable traffic flow, specific rules must be added to the NSGs to permit traffic from the on-premises network to the NC2 environment. Thisincludes specifying the appropriate source and destination IP ranges and the necessary ports and protocols.

References:

Azure Network Security Groups Documentation

Nutanix NC2 Networking Configuration Guide