If they share the same IP address this isn’t possible. Ping uses ICMP echo requests and replies and ICMP doesn’t use ports that could be NATted to different machine.
You’ll need to bridge the vNIC to the local network so each VM gets a different IP. Alternatively, you could connect both to an internal, entirely virtual network – depending on what the hypervisor can be configured to do.
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solved networking a virtual machine from another on the same host? [closed]