How to make friends netgear jwnr2000v2 with L2TP + IpSec?

Question

NETGEAR

Hello.
Is available Netgear jwnr2000v2, the provider gives the Internet through PPPoe.
Connected to PC directly.
Everything works as I need, but there is one unpleasant nuance for me.
The problem is this:
I can't connect to the VPN server via L2TP + IPSec. I create a new connection in Windows 7, enter the correct parameters and get the error "789: The L2TP connection attempt failed because the security layer encountered a processing error during initial negotiations with the remote computer". I'm using the regular client.
Tried on Linux, xl2tpd returns [ERROR 300] 'IPsec' failed to negotiate or establish security associations.
I connect directly, bypassing the router - everything works fine. With a router - does not work.
I repeat: I have a PPPoe provider, I don’t have an external IP, that is, I’m behind a nat.
Nobody faced such a problem? Can you tell me what could be the reason, and how can I diagnose this (the router's "log" is empty)?
Firmware Version: V1.0.0.11_1.0.1