Purchased my AT&T Wireless 3G card about 2 months ago. Has worked flawlessly since then, up until today. Out of no where, when trying to connect with a full 3G signal available, an error message stating Error 668 caused the connection to terminate. I tried the usual problem solving of removing the aircard and reinserting it, restarting the ATT connection manager, and restarting my laptop. Nothing worked, and it continued to produce the Error 668 message.
As I would rather squeeze turnip juice than call AT&T Wireless for any technical support issues, I tried A few Google searches which netted some promising results. While I am not sure exactly what fixed my problem, it is now working again without any hardware replacement. Feel free to try the methods below.
Reinstall the Firmware
- If you have a different model or Mac OS, you can start at the Sierra Support website
- Otherwise, visit the 881 AirCard Support Downloads page for Windows
- Download and run the firmware application, while keeping your aircard plugged into the PCMCIA slot.
- Some people mentioned that installing the Connection watcher utility from the support downloads page may also help with this issue, but I did not need to use it.
After reinstalling the firmware, I attempted to connect again but still received the same error 668 code. I then moved to this next little workaround.
Install New ATT Connection Profile Using wap.cingular
This is what I think finally fixed my problem, but it did not work without first reinstalling the firmware.
1. Edit connection profiles in ATT Wireless Connection Utility
2. Click the “Add” button on the profile manager window, then select “AT&T” and hit next.
3. Change isp.cingular to wap.cingular, and leave all the other input boxes as is. My result looked like this:
4. Hit next, make sure both radio buttons are select to “Obtain IP Address Automatically” and hit next again.
5. Give your new profile a name, I used AT&T (2). I changed the connection options window to “Automatic” from the default manual, and that seemed to work for me.
6. Hit Finish, close out of the profile manager, select the connections drop down window in the AT&T connection utility, and then select the new AT&T (2) connection profile that we just created.
Hope this was some help to you. Please post in the comments if this did or did not work for you.
Matt is a serial entrepreneur who is obsessed with technology. 
There are 10 comment(s) so far ;)
[...] mostly reliable, can sometimes be buggy on Windows Vista. At one point I received the dreaded Error 668 but was I eventually able to fix it. The problems have been few and far between, and would not be [...]
The firmware couldn’t install because the program “failed to find the device.” So I still had the problem. I spoke with AT&T and I was able to connect at 2G but not 3G. Not sure what to do now.
I cannot thank you enough for helping us. I had no trouble with my Sierra device and my Mac, but my husband struggled for hours with his and his Vaio. After we got partway through the problem by using the device manager and disabling the firewall and anti-virus and reloading the program, it still took what you laid out here to get us up and running. This was very important to us as we are out of town for a week and a half and really, really needed internet access. Thank you thank you thank you!
I have the AT&T wireless card. I can only stay connected for about ten minutes, regardless of what computer I’m on. I brought my aircard into the AT&T shop and was given a new one. Same problems. I was even told I am in one of the best areas for reception. I feel sorry for the people who are in bad reception areas!
Worked like a charm. Thanks.
I am currently trying the fix described above and while typing this comment, it just crapped out. This really sucks. Now on top of all of the disconnects (I can stay online from 4-8 minutes), now my web pages are hitting “timed out”. I receive a 3G signal on my cell phone, but have never gotten it on my sierra 881.
I use Windows XP on two machines (one laptop one desktop). The first time I installed the card (I have a USB Sierra Wireless Mercury card) on the laptop it worked just fine right away. However, when I tried it a second time a day later, it gave the 668 error. Then I installed on the desktop and got 668 right away. Then I changed isp.cingular to wap.cingular just like you said and it worked on the desktop and laptop.
I think the error is not b/c of you signal but because of this isp vs wap thing (why ATT can’t get this right is beyond me lol).
thanks for the solution!
Setting the access point to wap.cingular was what worked for me. Weird that AT&T and Sierra do not explain this on their support pages - would have been helpful to have a big note on the support page for this product since its such an easy fix. Thanks for posting this info.
Thanks a lot. But I have skipped the first step of updating the firmware knowing my device never worked. Then I proceeded to the second step of updating wap.cingular information. It worked just fine I appreciated.
Your solution worked perfectly!