Gost "Linux" machine from VPN not pingable from local network

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Hi
I'm facing a strange behavior: I have 2 EFW connected by a VPN.
In the services list of the client machine I can see a host named "Linux" with a MAC that indead is owned by a physical machine and I can even ping it from the outer network, but if I connect (RDP) to a remote machine in the same network of the client and try to ping the same machine it is not pingable.
I'm starting to think that my firewall is corrupt....
What do you think about it?

Thank you