VPN ping problem with Android

[dev-innov]

Hi everyone !
I'm here to explain a problem that I have about softEther VPN.
First, I have built a local VPN with computers and Android smartphone.

I have a VPN server on a Debian OS with the cmd server. This is my configuration :
Protocole : L2TP /IPsec (for enable Android communication)
I enable SecureNAT for having access to Virtual DHCP (His IP is 192.168.30.10)
I use a virtual DHCP for setting IP adress from 192.168.30.30 to 192.168.30.60
The virtual NAT is disabeled
I've set differents users with password.

All my clients (Windows and Android) can connect to to my VPN, and they've got "good" IP.

My problem is about the communication :
My computers can ping each other computers but not the smartphone.
And the smartphone can ping computers but not each others smartphone.
For good communication, I've disabled firewall on computers, but I can't do this on Android.
I give you a picture here : http://hpics.li/ab2f143

:)
Can you explain to me where is my mistake ?
Sincerely, Gorecki S.

[thisjun]

I think Android can't answer ping.
Please try to another way to confirm.

[dev-innov]

Hi thisjun, first thanks you for your reply.
I think android can answer to a ping because a computer can ping it. Moreover, one of my Android device can ping one other ... (they're all under Android 4.4).

[thisjun]

Can you check communication other than ping?

[kh_tsang]

I tried to ping my android phone with the IP assigned to the phone by VPN from my own computer. I find that Android phone responds ping with its own public IP address assigned by the mobile ISP.