Error 721 The Remote Computer Does Not Respond
I have FINALLY resolved an ongoing issue with our VPN connections that we have been experiencing for over a year now. I will share these findings with this forum in case others can benefit from our situation. First let me explain the error 721 vpn windows xp problem. The Problem: It can take up 6 retries for any remote user to successfully created error 721 directv a remote PPTP connection to our servers. Whenever we try to connect it display the following message: Verifying username and password... And it sit there displaying this message for about 30-40 seconds, then it says: "error: 721 The remote computer did not respond." Network Setup: We have two netopia routers on our network. They both have their own separate WAN connection (we use a lot of bandwidth, hence the need for two WAN connections). One RAS server is configured to use one router as it's gateway, and the other RAS server uses the second router as it's gateway. When PPTP connections are made, the connection comes in and back out the same router (this I made sure). We use a multi-NAT for routing service request to internal servers. FTP, WWW, RDP, PCAnywhere, SSL, PPTP, MAIL, etc...all these services are routed to internal servers/workstations. We have approximately 32 public IP addresses, hence why we use Multi-NAT for routing public services to internal servers. Everything works perfectly, EXCEPT PPTP (VPN) connections. We have struggled with this for a year now. For whatever reason, it struggles to make a successful connection to our RAS servers. Like I said, it can take up to 6 retries to successfully connect to our RAS servers (up to 30 retries if the remote user is behind a Linksys router). The Fix: Today, I decided to try something different. I decided to use the router's public IP address for PPTP requests, instead of one of the other public IP addresses our ISP assigned us, and simply forward PPTP (TCP 1723 & IP 47) requests to the internal servers. Therefore, the only difference is that I am using a pingable IP address which happens to belong to the router instead of using one of the public IP addresses I have NATed. For whatever reason, this solved our problem with connecting to the RAS server. We no longer have to retry up to 6 times to successfully connect. Conclusion: I have NO clue as to why I have to use the router's public IP address rather than any of the other 31 public IP addresses our ISP assigned to us. This was ONLY an issue with the PPTP service. All the other services work perfectly with the router's Multi-NAT table. In the end I don't know whether it's a router issue
Start here for a quick overview of the site Help Center Detailed answers to any questions you might have Meta Discuss the workings and policies of this site About Us Learn more about Stack Overflow the company Business Learn more about hiring developers or posting ads with us Server Fault Questions Tags Users Badges Unanswered Ask Question _ Server Fault is a question and answer site for system and network administrators. Join them; it only takes a minute: Sign up Here's how it works: Anybody can ask a question Anybody can answer The best answers are voted up and rise to the top VPN returning 721 error despite successful logins to/from other locations up vote 2 down vote favorite I am trying to connect a http://www.pcreview.co.uk/threads/error-721-finally-resolved.1574450/ couple of Win XP desktops at a remote site, to the server (SBS 2008) of a central site, using a PPTP based VPN. When I try to connect, I get the error "Disconnected. Error 721: The remote computer did not respond." Here is the strange part: The remote PCs can successfully dial out to another server using VPN. Similarly, I can successfully dial into the central site from my work PC. The remote computers are dialling out through a Netgear DG834Gv4 (latest http://serverfault.com/questions/110009/vpn-returning-721-error-despite-successful-logins-to-from-other-locations firmware), and the server is behind a Draytek 2820. I have also tried using the Draytek as the VPN endpoint (instead of it doing pass-through), which again worked successfully from my work PC, but gave the same result from the remote site. I can ping the central site from the remote one, no problem. I can also telnet into port 1723 from the remote site. The central server is a domain controller with AD. At some point in the past, the remote PCs were successfully logged onto the domain, so now log into that (but obviously can't connect). The remote PCs are on a network which contains another SBS 2008 domain/domain controller/AD/server. However, the remote PCs are using the DG834 as their DNS/DHCP/etc. I and my colleagues are totally stumped - we know each end is fine independently, but for some reason they won't work together. We don't think that it's authentication; it doesn't seem to get that far. There's nothing in either router's firewall which would prevent one the remote IP but not my work IP. The MTU of the DG834 has been changed to match the Draytek. Any ideas? vpn pptp share|improve this question asked Feb 5 '10 at 15:28 Andrew C Ok, I've tested the VPN from one of the PCs from the other domain which is at the remote site, and it has the same response - implying that there is a problem with that site
for Help Receive Real-Time Help Create a Freelance Project Hire for a Full Time Job Ways to Get Help Ask a Question Ask for Help Receive Real-Time Help Create a Freelance Project Hire for a Full Time Job Ways to Get Help Expand Search Submit Close https://www.experts-exchange.com/questions/21334514/VPN-question-error-721-Remote-computer-did-not-respond.html Search Login Join Today Products BackProducts Gigs Live Careers Vendor Services Groups Website Testing Store Headlines Experts Exchange > Questions > VPN question - "error 721: Remote computer did not respond" Want to Advertise Here? Solved VPN question - "error 721: Remote computer did not respond" Posted on 2005-03-02 Software Firewalls Hardware Firewalls Networking 3 Verified Solutions 11 Comments 34,429 Views Last Modified: 2013-11-16 I'm trying to setup VPN against a Windows 2003 server. Client is error 721 XP pro. The server is behind a router that run NAT. When I'm connecting to the VPN server directly to the internal IP I connnect without problems. Our ISP have setup the NAT on the router to temporarily allow all IP traffic to this external IP. But when I try to VPN connect to external IP it hangs with message "verifying username/password" and then I get "error 721: Remote computer did not respond". Any ideas what error 721 the might be wrong? Are any particular settings on the router needed to make this work? 0 Question by:rj2 Facebook Twitter LinkedIn Google LVL 16 Best Solution bysamccarthy You will need to verify that the ISP is letting the traffic IN from the external IP. You need to allow port 1723 TCP for PPTP and GRE, IP Protocol 47. You will also need to port forward 1723 to the Go to Solution 11 Comments LVL 16 Overall: Level 16 Networking 6 Software Firewalls 4 Hardware Firewalls 3 Message Accepted Solution by:samccarthy2005-03-02 You will need to verify that the ISP is letting the traffic IN from the external IP. You need to allow port 1723 TCP for PPTP and GRE, IP Protocol 47. You will also need to port forward 1723 to the Nat IP address of the Windows 2003 server doing the VPN. So, your external client sends a VPN request to the external IP. The router sees this on port 1723 and then will forward that on to the IP address of your server. 0 LVL 10 Overall: Level 10 Message Author Comment by:rj22005-03-02 Well, the ISP says that they believe everything is ok on the router, and it is setup according to the url below. http://cisco.com/en/US/tech/tk827/tk369/technologies_configuration_example09186a00800949c0.shtml So if this problem is on the server, how do I fix it? Could setting up RADI