If you're reading this then you already know the microcell and AT&T's support for the most part suck. I've had my microcell since the first availability in the Seattle area almost 2 years ago.
I've generally always had some sort of problem (random crash, iphone sync, outgoing voice lag), with power cycling everything as my main solution. In the last few months I was getting the red 3G flash every night and 2 weeks ago after doing much internet reading I finally called AT&T to see what they could do on their end.
My prior setup, Priority mode (only in the hope that it reduced router problems, no noticeable improvement), Apple EBS wireless router, Motorola 6120 cable modem, iPhone 4, Comcast internet, a few wireless devices and 1 wired computer.
After speaking 30+ min with the nice, but help limited tech, we went the deactivate/re-activate route. - No Go.
My microcell only powered on and then the Ethernet light, no GPS, it would flash the 3G 10 to12 times then do nothing for about 5 minutes then power cycle itself with no improvements. After waiting 6 hours in the hope something would happen or that new software was being pushed I began to try different things. I hit the reset button, power cycled, put in priority location, deactivated/re-activated a few more times.
No Dice, it looked like the deactivate or software push (as the tech mentioned as my device was "old") killed my microcell. She did send me some info on the router ports to open, which with an apple is a bit of a pain and I generally had it in priority mode so it didn't matter.
I did open the ports and use the MAC address for a direct connection after receiving double NAT messages from the router if it was in priority mode and moved the microcell behind my router.
Called again next day with even less help, this time the tech used "I hope & I guess" more than anything else, with the end solution being my microcell was dead and I'd have to buy a new one. F that! Telling her it worked (although limited) before following the prior tech's advice and that they would need to replace it fell on deaf ears. Although I would've fought more later.
ANYWAY - The FIX
(Standard caveat applies here, and I'd only do this on a non-functioning microcell like mine.)
The RESET button: If you think about it, the device is actually a Cisco product and therefore the hardware design is theirs and not AT&T's. In this hope, I proceeded to spend the next hour hitting the reset button in the vain hope that at some point in time it would truly reset the device and eventually act as a new device with AT&T and work again.
I've read the "don't hit the reset button" posts and can't say one way or another if this is valid (and have pressed, but not held the button before), but what I can say is that after holding down the reset button (for up to 5 minutes) the microcell did finally "reset" and instead of just hanging, it began flashing the GPS and 3G signals. After one last deactivate/re-activate and 30 minutes I received the activation text and haven't a problem with it since. I'd also say the call quality has improved and that callers can hear me a lot better now.
What I did:
I kept on pushing and holding the reset button noting if anything changed after a certain time period or double push, push power cycle, etc. over and over. Eventually the GPS and 3G lights began to flash as they normally would on a power up. What I can only guess is that at some point the device finally dumped whatever old or bad software/settings that was making it crash and was able to reestablish a connection w/ AT&T.