Problems with Cisco Anyconnect - VPN client driver error

[Brian Lund]

Hello,

We have a customer who has provided us VPN access and it has been working great so far, but after the customer updated to the latest version of AnyConnect client software, version 4.4.01054, I cannot connect to their network anymore! AnyConnect tries to connect, then says "Repairing" and after a while it just disconnects.

It seems that my computer is the only one who is not able to connect after the update, all the customers own users can connect, I can even connect with my username/password from another computer or virtual machine. But from my physical computer I cannot.

I have tried pretty much every possible solution that I could google except for formatting my PC! I have tried to reinstall the client, I have tried deleting leftover files in ProgramFiles and ProgramData, I have tried changing some suggested settings in the registry editor and I have tried stopping CryptSvc service and running an "esentutl" command... All to no avail, it still does not work!

Formatting my PC is not really an option as it would require me to send it to our IT department which is in another country and with shipping forth and back and them configuring it and me reinstalling whatever software they did not afterwards I would probably be out of proper work for at least a week if not two weeks!

Here a copy from the log of what happens when I try to connect.

     10:05:45    Contacting *HOSTNAME EDITED OUT*
     10:05:50    User credentials entered.
     10:06:06    User credentials entered.
     10:06:06    Establishing VPN session...
     10:06:06    The AnyConnect Downloader is performing update checks...
     10:06:06    Checking for profile updates...
     10:06:06    Checking for product updates...
     10:06:06    Checking for customization updates...
     10:06:06    Performing any required updates...
     10:06:06    The AnyConnect Downloader updates have been completed.
     10:06:06    Establishing VPN session...
     10:06:06    Establishing VPN - Initiating connection...
     10:06:06    Establishing VPN - Examining system...
     10:06:06    Establishing VPN - Activating VPN adapter...
     10:06:06    Establishing VPN - Repairing VPN adapter...
     10:06:14    Disconnect in progress, please wait...
     10:06:14    The VPN client driver encountered an error.  Please restart your computer or device, then try again.
     10:06:14    AnyConnect was not able to establish a connection to the specified secure gateway. Please try connecting again.
     10:06:14    Ready to connect.

[Brian Lund · Accepted solution]

I solved the problem, after unchecking the IPv6 protocol for the AnyConnect networks adapter it works again!

[John Telford]

Thanks for the solution Brian!
I had the same issue today (Windows 7, Client 4.4.-3-34)
In my case I had been testing a new network and had installed nmap (zenmap GUI) for windows.
It had added an additional driver to the network interfaces. Once I disabled "Npcap Packet Driver" it was working again.

[netops5]

Thank you!! Npcap packet driver was the issue for me as well.

[raakeshbsht86]

This Worked for me...Thanks a lot for suggesting this.
So I did the following-
1) Go to properties of CiscoAnyconnect under your Networks.
2) Disable/Unchecked Npcap Packet Driver(NPF) 
3) Try connect now..Worked!! 
if this doesn't work...guys can try Disabling IPv6 also.
Thanks.

[BobZ]

That worked for me too!  Many thanks...

[rjr]

Thanks for posting this. I never would have thought to uncheck IPv6. I would have assumed the TCP protocols (IPv4 & 6 were configured by default). I think the issue happened after a Cisco update occurred (which set IPv6) and then, since I put my laptop to sleep each night, it worked for several weeks until I had to reboot the system at which time the connection failure loop occurred as noted above. BTW, Cisco was no help. Thanks very much for posting this!

[badmotherfuçker]

Thanks for this post. I'm running AnyConnect v3.1.05160 on OSX High Sierra and was suffering from the "please reboot" prompt until I disabled IPv6. FYI, I didn't even need to reboot. Just disabling IPv6 allowed me to connect.

[Carloscosta]

worked for me also on 4.5 wow

[raakeshbsht86]

This didn't work for me.
So I did the following-
1) Go to properties of CiscoAnyconnect under your Networks.
2) Disable/Unchecked Npcap Packet Driver(NPF) 
3) Try connect now..Worked!! 
you can try Disabling IPv6 also if this doesn't work.
Thanks.

[mrmjforrest4]

I found a similar issue with Trend Micro LightWeight Filter Driver on the Anyconnect adapter settings.  I unchecked the box and had the user test his VPN and it stayed connected.  No more drops.

[bsgdsube1]

Thanks a lot.

[PBurns]

This post saved my hide today so much so that I created an account here only to say thank you, so 

Brian Lund, Thank you!!

Your story is almost the same as mine. My AnyConnect VPN software is provided by my customer. Yesterday they upgraded to 4.10 from 4.06. When I installed their provided upgrade, my VPN which was working fine up until now stopped working with the error message "AnyConnect was not able to establish a connection to the specified secure gateway. Please try connecting again." followed by another error that overlaps it "The VPN client driver encountered an error. Please restart your computer or device, then try again."

What I did was I had to completely uninstalled and re-installed multiple times the AnyConnect software. Then I removed the IPv6 check from the Cisco network adapter, only then it connected. It really is trial and error following the advice from Brian. 

I've experienced this issue on Windows 2020 H2 update. 

[riwakefi]

I had this exact same problem, none of these fixes helped.

I stumbled onto a forum that suggested Webroot AntiVirus was causing this issue, and a full uninstall of Webroot was the fix. And that DID fix my issue.

Wanted to post that info to this thread for others to see, if none of the tricks the folks mention in this post work, it could be your antivirus software, FYI.