We are having trouble when test the VPN remote-access with the above error. It returned domain name successfully when we run nslookup "router_IP" in window CMD but it keeps prompting the error window when we connected via Cisco Any Connect 3.1. We have Router cisco 3925, iOS Version 15.1(1)T1. Please help.

Updated1: Router's config

aaa new-model  
aaa authentication login AuthenList local  
aaa authorization network vpn-group local  
username vpn1 secret 5 xxxx  

crypto isakmp policy 10  
 encr 3des  
 hash md5  
 authentication pre-share  
 group 2  

ip local pool remote-pool  

crypto isakmp client configuration group cisco  
 key xxxx  
 pool remote-pool  

crypto ipsec transform-set set1 esp-3des esp-md5-hmac  
crypto dynamic-map map1 10  
 set transform-set set1  

crypto map map1 client authentication list AuthenList  
crypto map map1 isakmp authorization list vpn-group  
crypto map map1 client configuration address respond  
crypto map map1 10 ipsec-isakmp dynamic map1  

interface GigabitEthernet0/1  
 ip address A.B.C.D xxxx  
 ip nat outside  
 ip virtual-reassembly  
 duplex auto  
 speed auto  
 crypto map map1  

The error:

The VPN connection failed due to unsuccessful domain name resolution

when I entered the domain name of router's interface g0/1 from nslookup (server**


I could do forward nslookup but reverse lookup (domain name -> IP) returns failed. Is it a problem?

In router's config:
ip name-server

  • You need to edit your question to include the router configuration. Also, include any logs and exact error messages.
    – Ron Maupin
    Commented May 1, 2017 at 15:51
  • @RonMaupin I updated it, please help
    – SpiderlinK
    Commented May 1, 2017 at 16:10
  • 1
    If there is no DNS name to address resolution, then you can't use the DNS name. You could use the IP address.
    – Ron Maupin
    Commented May 1, 2017 at 16:40
  • Hi, when I entered the IP address, it said that "Could not connect to server. Please verify Internet connectivity and server address". I'm pretty sure that Internet and IP address are OK, correct.
    – SpiderlinK
    Commented May 1, 2017 at 16:57
  • Did you configure DNS resolution on the router?
    – Ron Trunk
    Commented May 1, 2017 at 17:07

2 Answers 2


Seems that configuration of SSL VPN is not completed or incorrect (according to provided part of config). Try to read this guide and do a walk thru steps in it.

  • I got this error when followed your instructions. Do you know why? R2#copy tftp: flash:/webvpn/ Address or name of remote host []? Source filename []? anyconnect-win-3.1.03103-k9.pkg Destination filename [/webvpn/anyconnect-win-3.1.03103-k9.pkg]? Accessing tftp:// Loading anyconnect-win-3.1.03103-k9.pkg from (via FastEthernet0/0): ! %Error opening slot0:/webvpn/anyconnect-win-3.1.03103-k9.pkg (No such device)
    – SpiderlinK
    Commented Jun 7, 2017 at 2:14
  • The same error with copy tftp: flash: %Error opening slot0:/webvpn/anyconnect-win-3.1.03103-k9.pkg (No such device)
    – SpiderlinK
    Commented Jun 7, 2017 at 2:16
  • @bim in enable mode execute dir all-filesystems and look for what file storages you have. On my ASA5515x there's disk0: device. Commented Jun 7, 2017 at 6:48
  • @ Andrey Hi, this is a test env on GNS3, I test it before go on real device but when I hit above command, it only shows system, tmpsys and nvram
    – SpiderlinK
    Commented Jun 8, 2017 at 1:20
  • @bim with what virtualization you're running Cisco 3925 in GNS3? Commented Jun 8, 2017 at 12:22

I received this message today while working at home on my FDA laptop. "The VPN connection failed due to unsuccessful domain name resolution". When I called FDA's helpdesk I found that we connect to a different VPN from Cisco AnyConnect Secure Mobility Client. It's called VPN-Preferred. When I chose that instead of "Remote Connection" I connected to VPN-Preferred in a snap. No more issues.

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