I had a NAT firewall.

Open up IP50,IP51, UDP500, TCP1701, UDP1701, UDP4500 for the VPN server
virtual IP with static NAT.

Somehow Windows XP PRO client L2TP/IPSEC/Preshared key keeps having a 678
error with remote computer did not response.

I had read that L2TP/IPSEC will not work with NAT, is there really no way
through it?

You can refer to the following KB articles for your case:
http://support.microsoft.com/kb/818043/
http://support.microsoft.com/?kbid=912213

--
Regards,
Janani Vasudevan [MSFT]
Software Design Engineer/Test
RRAS, Windows Enterprise Networking

http://blogs.msdn.com/jananiv

RRAS blog: http://blogs.technet.com/rrasblog

[This posting is provided "AS IS" with no warranties, and confers no
rights.]

"David" <(E-Mail Removed)> wrote in message
news:E9BF6143-3B9D-4827-ABDA-(E-Mail Removed)...
>I had a NAT firewall.
>
> Open up IP50,IP51, UDP500, TCP1701, UDP1701, UDP4500 for the VPN server
> virtual IP with static NAT.
>
> Somehow Windows XP PRO client L2TP/IPSEC/Preshared key keeps having a 678
> error with remote computer did not response.
>
> I had read that L2TP/IPSEC will not work with NAT, is there really no way
> through it?

Thanks Janani,

After changing the reg key, I managed to connect.

"Janani Vasudevan [MSFT]" wrote:

> You can refer to the following KB articles for your case:
> http://support.microsoft.com/kb/818043/
> http://support.microsoft.com/?kbid=912213
>
> --
> Regards,
> Janani Vasudevan [MSFT]
> Software Design Engineer/Test
> RRAS, Windows Enterprise Networking
>
> http://blogs.msdn.com/jananiv
>
> RRAS blog: http://blogs.technet.com/rrasblog
>
> [This posting is provided "AS IS" with no warranties, and confers no
> rights.]
>
> "David" <(E-Mail Removed)> wrote in message
> news:E9BF6143-3B9D-4827-ABDA-(E-Mail Removed)...
> >I had a NAT firewall.
> >
> > Open up IP50,IP51, UDP500, TCP1701, UDP1701, UDP4500 for the VPN server
> > virtual IP with static NAT.
> >
> > Somehow Windows XP PRO client L2TP/IPSEC/Preshared key keeps having a 678
> > error with remote computer did not response.
> >
> > I had read that L2TP/IPSEC will not work with NAT, is there really no way
> > through it?
>
>
>