Error 781 on VPN that worked before

My boss has successfully VPNed into our network before. Today he recieved
an error 781 (error 781: The encryption attempt failed because no valid
certificate was found) when trying to VPN in from a hotel-provided broadband
connection. I first suspected that basic internet connectivity had not been
established, so I had him do an IPCONFIG. The hotel had apparently
assigned him a class A address (10.x.x.x), and I verified that he had also
been configured with an appropriate gateway and DNS servers. When I had him
ping the IP of the VPN server he got replies. Could there be a certificate
problem that didn't exist a couple of days ago? I disconnected my machine
from our office network, established a dial-up to the internet, and
successfully VPNed in to the same server, but he still could not.

Any ideas? All help appreciated.

Thanks,

Bryan

quoted from http://www.ChicagoTech.net
Error 781 - Encryption Failed

Symptom: When connecting to a VPN server, you may receive this Error 781:
The encryption attempt failed because no valid certificate was found.

Resolution: If your VPN client is trying to use L2TP/IPSec for the VPN
connection, you may receive above message. What you need to do is switching
to a PPTP VPN connection, which doesn't need a certificate. To do this,
open the properties of the VPN connection, choose the Networking tab, and
change the "Type of VPN" to PPTP VPN (default is Automatic). Also make sure
you have good connection. Sometimes, poor connection can cause this issue
too.


--
For more and other information, go to http://www.ChicagoTech.net

Don't send e-mail or reply to me except you need consulting services.
Posting on MS newsgroup will benefit all readers and you may get more help.

Robert Lin, MS-MVP, MCSE & CNE
Networking, Internet, Routing, VPN, Anti-Virus, Tips & Troubleshooting on
http://www.ChicagoTech.net
This posting is provided "AS IS" with no warranties.

"Bryan Linton" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
> My boss has successfully VPNed into our network before. Today he recieved
> an error 781 (error 781: The encryption attempt failed because no valid
> certificate was found) when trying to VPN in from a hotel-provided
> broadband
> connection. I first suspected that basic internet connectivity had not
> been
> established, so I had him do an IPCONFIG. The hotel had apparently
> assigned him a class A address (10.x.x.x), and I verified that he had also
> been configured with an appropriate gateway and DNS servers. When I had
> him
> ping the IP of the VPN server he got replies. Could there be a
> certificate
> problem that didn't exist a couple of days ago? I disconnected my machine
> from our office network, established a dial-up to the internet, and
> successfully VPNed in to the same server, but he still could not.
>
> Any ideas? All help appreciated.
>
> Thanks,
>
> Bryan
>
>

Thanks for the info. I have a few questions:

-- Since he has successfully connected in the past from the same client
computer, can it be assumed that the issue is not L2TP/IPSec vs PPTP?

-- If it isn't, can it be assumed that an issue exists with the
quality/nature of the internet connection?

-- What are the security implications of using PPTP instead of L2TP/IPSec?
(I know IPSec is considered a superior protocol (i.e., more secure), but how
concerned should I be? What type of vulnerability are we talking?)

-- When you say "poor connection", how do you define that?

-- We are using the default of "Automatic", so which one does it try to use
first? L2TP or PPTP?

Thanks again,

Bryan



"Robert L [MS-MVP]" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
> quoted from http://www.ChicagoTech.net
> Error 781 - Encryption Failed
>
> Symptom: When connecting to a VPN server, you may receive this Error 781:
> The encryption attempt failed because no valid certificate was found.
>
> Resolution: If your VPN client is trying to use L2TP/IPSec for the VPN
> connection, you may receive above message. What you need to do is
switching
> to a PPTP VPN connection, which doesn't need a certificate. To do this,
> open the properties of the VPN connection, choose the Networking tab, and
> change the "Type of VPN" to PPTP VPN (default is Automatic). Also make
sure
> you have good connection. Sometimes, poor connection can cause this issue
> too.
>
>
> --
> For more and other information, go to http://www.ChicagoTech.net
>
> Don't send e-mail or reply to me except you need consulting services.
> Posting on MS newsgroup will benefit all readers and you may get more
help.
>
> Robert Lin, MS-MVP, MCSE & CNE
> Networking, Internet, Routing, VPN, Anti-Virus, Tips & Troubleshooting on
> http://www.ChicagoTech.net
> This posting is provided "AS IS" with no warranties.
>
> "Bryan Linton" <(E-Mail Removed)> wrote in message
> news:(E-Mail Removed)...
> > My boss has successfully VPNed into our network before. Today he
recieved
> > an error 781 (error 781: The encryption attempt failed because no valid
> > certificate was found) when trying to VPN in from a hotel-provided
> > broadband
> > connection. I first suspected that basic internet connectivity had not
> > been
> > established, so I had him do an IPCONFIG. The hotel had apparently
> > assigned him a class A address (10.x.x.x), and I verified that he had
also
> > been configured with an appropriate gateway and DNS servers. When I had
> > him
> > ping the IP of the VPN server he got replies. Could there be a
> > certificate
> > problem that didn't exist a couple of days ago? I disconnected my
machine
> > from our office network, established a dial-up to the internet, and
> > successfully VPNed in to the same server, but he still could not.
> >
> > Any ideas? All help appreciated.
> >
> > Thanks,
> >
> > Bryan
> >
> >
>
>