Error 733 al intentar conectar un cliente por VPN con el servidor

Lee a partir de aqui:
" 1.. The router supports "VPN pass-through" (be aware that different
routers may use different terms). Other terms that are normally associated
with this are: "IPSec" and "L2TP".



error 733: could not agree on PPP control protocols


Symptom:
When trying to establish a VPN connection to a computer the following error
is encountered:

Checking network protocol connections...

TCP/IP CP reported error 733: Your computer and the remove computer could
not agree on PPP control protocols

Cause:
The client (i.e. your computer) and the server (i.e. the computer you are
trying to establish a VPN connection to) cannot agree on a common set of PPP
control protocols. This is a very generic error and can be caused by a
number of things.

Possible Remedies:
a.. On the client disable the "Negotiate multi-link for single link
connections" setting. To do this:

1.. Start > Settings > Control Panel

2.. Open "Network and dial-up Connections"

3.. Right click the VPN network connection giving the problem and select
"Properties"

4.. On the "Networking" tab, click "Settings"

5.. Clear the check-box "Negotiate multi-link for single link
connections"

a.. If the server is connected to the internet via a router then it may be
that the router does not support VPN connections. Ask the server
administrator to check that:

1.. The router supports "VPN pass-through" (be aware that different
routers may use different terms). Other terms that are normally associated
with this are: "IPSec" and "L2TP".

2.. The router is configured to pass through VPN connections to the
necessary server.
NOTE: It is not sufficient to simply forward ports 1723 and 47. Port
1723 needs to be forwarded, but what needs to be forwarded is IP Protocol 47
(GRE) not port 47. This is normally done via an explicit setting on the
router. If the router does not appear to support this then investigate
whether a bios upgrade is available for the router.

a.. Check that the server and client agree about who is assigning or
specifying TCP/IP addresses. (It is common to allow the server to specify
the TCP/IP address.)

b.. At the VPN server ensure that there are IP addresses available to
allocate. The default setting for incoming TCP/IP is to "(o) Assign TCP/IP
addresses automatically using DHCP" however if there is no DHCP server on
the machine then instead select "(o) Specify TCP/IP addresses" and enter a
suitable range.

c.. Check that the network protocol you are using (typically TCP/IP but
could be NetBEUI) is also listed at the server end. (Note: Adding a protocol
to an NT4 server will require a reboot to take effect.)