There's no such thing as a stupid question, but they're the easiest to answer.


Networking Networking
Search Search
Search for:
Tech Support Guy > > >

Windows VPN error 721


allenle37's Avatar
allenle37 allenle37 is offline
Member with 71 posts.
Join Date: Jun 2006
Location: Dallas, TX
Experience: Intermediate
25-Aug-2008, 01:20 AM #1
Windows VPN error 721
I am completely stumped at this point:confused. Hopefully someone can help me resolve this issue.

My current setup is a D-link dir655 router and a PC running Vista Ultimate accepting incoming connections. When I try to connect through the windows VPN it gets stuck at verify user name and password then gives me a error code 721. I have googled this issue and only found that I need to permit GRE protocol 47 and forward port 1723 to the PC accepting incoming connections.

I do not know how to permit GRE protocol 47 on my router. I read on a forum:
(Screen shot attached)
Advanced > Firewall Settings
ALG: make sure these are checked:
- IPSec (VPN)

Which should allow this to work, but still no go. To isolate the problem I tried making the Vista machine as the DMZ host and I am able to connect. So the problem lies with the firewall. Any ideas?
Attached Thumbnails
Windows VPN error 721-untitled.jpg  
JohnWill's Avatar
Computer Specs
Retired Moderator with 106,412 posts.
Join Date: Oct 2002
Location: South Eastern PA, USA
25-Aug-2008, 10:18 AM #2
Since you have IPSec (VPN) checked, that should already be enabled.

Have you tried upgrading the firmware to the latest version?
How about resetting the router to factory defaults and reconfiguring?

If neither of those work, try turning off SPI on the router as a test.
lexus37's Avatar
lexus37 lexus37 is offline
Junior Member with 17 posts.
Join Date: Jun 2006
Experience: Advanced
25-Aug-2008, 09:04 PM #3
Yes the firmware is upgraded to the latest version. I have not tried to restore factory defaults and reconfiguring. I'm currently out of town right now, but let me try that when I get home. I will get back to you this weekend. Thank you for the suggestion.
skinnywhiteboy's Avatar
Computer Specs
Member with 2,068 posts.
Join Date: Jan 2001
Location: Wayne, MI
Experience: Advanced
27-Aug-2008, 09:08 AM #4
Is the firewall on your vista machine set to allow those protocols through??
As Seen On

BBC, Reader's Digest, PC Magazine, Today Show, Money Magazine

Are you looking for the solution to your computer problem? Join our site today to ask your question. This site is completely free -- paid for by advertisers and donations.

If you're not already familiar with forums, watch our Welcome Guide to get started.

Are you having the same problem? We have volunteers ready to answer your question, but first you'll have to join for free. Need help getting started? Check out our Welcome Guide.

Search Tech Support Guy

Find the solution to your
computer problem!

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
Thread Tools

You Are Using: Server ID
Trusted Website Back to the Top ↑