zyxel SBG3300 VPN IPsec/L2TP

I have configured VPNs on a Zyxel SBG3300. When I connect remotely with a Windows or a MAC, I have access to network resources, but I'm unable to connect to the router console with its internal IP address.
Another point: I realize that I access for example the console of my NAS, but the ping does not respond.
Do you have an idea?
Thank you

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