Hi, @RCN Admin
I understand that you want to access your on-premises from "Customer Vnet" via "My Vnet".
Since VNET Peering Connections are non-transitive, "Customer Vnet" cannot access on-premises via "My VNet".
In order for "Customer Vnet" to access your on-premises, you need to connect between VNETs in a different way.
For example, VPN Gateway works transitively, so connect "My Vnet" and "Customer Vnet" with VPN Gateway.
Please refer to the following documents for the transitivity of network components.
https://video2.skills-academy.com/en-us/azure/architecture/reference-architectures/hybrid-networking/vnet-peering