09-06-2013 11:12:09 AM
I have poor cell coverage at home, so bought a Microcell. The setup and installation went fine. All lights solid green. iPhones say MCell. No problem with inbound or outbound calls. 5 bars of beautiful signal. Everything works!
Except.... a few times per hour, the 3G light starts flashing green again. Any calls in progress are dropped. iPhones quit showing MCell and switch back to weak tower signal (or simply show No Service). A few minutes later, the 3G light stops flashing, MCell indicator returns, and we're off to the races again. I cannot figure out what the problem is.
Some maybe helpful information:
1) I exchanged the Microcell, thinking it was a defective unit. The second one behaves the same way.
2) All of the phones configured in the MCell behave the same way (all show loss of MCell at the same time)
3) internet connection is 12Mbps DSL service from CenturyLink using a combo modem/router: Actiontec GT784WN (running latest firmware). Speed test on PC shows 800Kbps upstream and 8Mbps downstream.
4) The Microcell problem happens regardless of LAN traffic (even when network is basically idle).
5) I setup port forwarding as recommended in the Microcell troubleshooting guide. Made no difference.
6) The Actiontec modem doesn't support viewing or changing the MTU or IP fragment filtering
7) I've tried disabling auto-handoff in the Microcell configuration. Made no difference.
8) The Microcell is connected to the modem by ethernet cable through a 10/100 ethernet switch. I've tried it with other network configurations and it made no difference.
It would be helpful if someone at AT&T could pull the server logs and see what's happening on the backend server side. I'm running completely blind as to what the Microcell is doing and why it is becoming unhappy several times per hour.
Or maybe someone in the Community Forum has experienced this problem and knows how to resolve it.
I can go buy another DSL modem if the Actiontec modem can be shown to be the cause. I don't want to waste the money if it's not going to resolve the issue, though. Does AT&T have a recommended DSL modem that's known to work with the Microcell?
Thank you in advance for any help that you can provide.
09-06-2013 11:30:15 AM
Hi Brian. Did you try to connect the MicroCell directly to the modem without using a switch? The fewer devices you have between the MicroCell and the internet, the better. The blinking green 3G light usually means that you've lost connection to AT&Ts servers which, more times than not, is the result of your connection to your ISP. Disabling Block Fragmented Packets is important for proper connectivity. AT&T won't pull server logs unless the problem is widespread and then it's more than likely an upstream switch that is failing and needs to be replaced. The MicroCell can be touchy with it's requirements and even the slightlest variation (power, connectivity, etc) will cause it to lose connection even if the rest of your network doesn't have any problems. Most of the time, it is very stable and works with virtually all routers currently available and most combo router/gateways. AT&T can't recommend a specific router or gateway because there are too many different kinds out there and it's just impossible to keep up with firmware versions and LAN setups. They specifically list what is required to connect to AT&T and it's up to the end-user to determine if their router meets those requirments or if they can be modfied to meet them. See the links in my sig.
09-06-2013 12:03:11 PM
I appreciate your response.
Yes, I did try to connect the Microcell directly to the router, bypassing the ethernet switch. Made no difference.
I guess the evidence points to an incompatibility between the Microcell and the Actiontec GT784WN modem/router. I would be very curious to hear if anyone else reading this post has made that combination work. Maybe the Actiontec device is blocking IP fragments, which apparently the Microcell needs. It's unfortunately not a configurable parameter in the modem.
Even if AT&T can't recommend a DSL modem (and I can certainly understand why), maybe someone reading this post who has a working Microcell on a DSL connection, could reply and let me know what modem you're using.
09-06-2013 12:49:53 PM
We've had a few problems reported here with Actiontec modems and CenturyLink but that doesn't necessarily mean that they are the problem. Just an observation.
I have a Comtrend DSL gateway set in bridge mode and connected to an Apple Extreme Base Station (without TimeCapsule). It seems, and this is only anectdotal, that a separate router and gateway is a bit easier to work with and configure than the all-in-one's. Even though there are lots of users who have all-in-one's and they work just fine. I guess it depends on how you have your LAN setup and the ISP.
09-07-2013 08:24:09 AM
I would offer that another area of concern could be the quality of your internet connection via your ISP. Excessive packet loss could be causing the Mcell to drop its connection and then re-establish itself after a packet loss episode dies down to an acceptable level.
You might contact CenturyLink and ask them to come out to troubleshoot your line. They have equipment that can determine if your modem signal is within specs and can determine packet loss. There might be troublesome connections, amplifiers or repeaters within your node that could be detrimental to your Mcell's ability to maintain its connection with AT&T's network of servers.
Just a thought.....
09-07-2013 01:23:51 PM
Checking network quality is a really good idea. I appreciate the suggestion. Before I call up Centurylink, let me run a ping a test between a hardwired Linux machine on my LAN, and the far side IP (i.e. Centurylink side) of the DSL connection. I'll report back with results.
BTW, as part of the setup for the ping test, I tried out a ping with a 2000 byte packet and the "Don't fragment" flag set. As expected, ping complained that it couldn't send the pings because the packets need to be fragmented. Then I removed the flag and retried. No problem getting responses, so this, I believe, proves that the DSL modem/router is not blocking IP fragments. This can now be scratched off the list of possible culprits.
09-07-2013 01:35:17 PM
As both Avedis53 and myself alluded to (Avedis53 a bit more clearer), network quality is essential, and is sometimes something that we have no control over because only the ISP can correct that. It sounds like you have a good handle on network testing and knowledge so the approach your taking is very sound. Does you Linux box act as a server for your LAN? If so, maybe that connection is the culprit. Keep in mind that the MicroCell is very unforgiving to network "oddities" and as simple as a connection is usually the best approach, if possible. Do report back your findings because it may be useful to add to the Technical Guide for others with similar setups.
09-08-2013 09:16:17 AM
Hi OP and Avedis53,
Thank you both for your kind replies. The latest news on this end: I put the Mcell in the DMZ, which removes port forwarding as a potential issue, I believe. I ran a ping test from my Linux host, through the 10/100 switch, and out across the DSL link to the far side IP address. Pings were at 1/10 second interval and I sent about 200k pings. Only 3 packets lost, so the network quality looks good. I shutdown the Linux host. The Mcell still merrily flashes its 3G light a few times per hour, dropping calls along the way.
I think I've tried everything that can be done. After more than 2 weeks screwing around with the Mcell, it's time for it to go back to AT&T. Thank you, and Best Regards,
09-08-2013 10:15:44 AM
DSL is not my strong point as I have cable modem service through Charter. I'm assuming you have functioning DSL filters on your phone connections? While I doubt that a bad DSL filter is causing your problem with the Mcell, it's another step in your process of elimination to determine the source of the problem.
There are other parameters that can affect DSL line quality and perhaps one or more of those parameters are present that you can not measure simply by pinging an outside IP address and looking for packet loss.
IMO, the fact that you connected your Mcell directly to your modem/router and still experience your intermittent 3G flashing light problem leads me to think:
1.) Your Mcell could be faulty but since you've changed it out once already and have the same problem, that's probably not it.
2.) Your existing modem/router doesn't play well with the Mcell. You could try a different brand besides Actiontec and see if the problem still exists. If it turns out that the problem still exists, you could return the new modem/router to the store.
3.) Your DSL connection has issues. I would still recommend having CenturyLink test your line for potential problems.
When you said you are returning the Mcell, are you getting another replacement or are you through with trying to use one?
09-08-2013 02:29:02 PM
My feeling is that if your Linux box is between the MicroCell and CenturyLink, the problem could be there. There's just something to that configuration that the MicroCell doesn't like. Port forwarding wouldn't be the problem because that's how I have mine setup. If anything, that makes your connection more reliable because the ports that have to open are, and if you've set it up with a static IP address for the MicroCell that's about as stable and you can make it. Once you shutdown the Linux host, try to power cycle the MicroCell, deregister/reregister, or a hard reset.
09-08-2013 07:43:11 PM
I've decided to bail on the Mcell since I can't figure out what the problem is. I'll return it to AT&T and get my money back. I do computer engineering for a living, so it's vexing that I can't figure it out.
If anyone from Cisco or AT&T is reading this, it would helpful to have some kind of minimal status/diagnostic web interface on the Mcell. The fact that it's a black box makes debugging problems essentially impossible.
Pending better cell coverage, I do have a work around. I've moved to a voip client on the iphone. This works fine since I have excellent wifi in the house. In case anyone is interested, the client is Softphone by Acrobits. The client will connect basically to any voip provider. I've chosen CallCentric, but there are many others. For outbound calls, the client makes the call through CallCentric. The sucky part is that callerID on the recipient phone does not show my iphone number. Rather it shows the voip number. For inbound calls, I forward my cell phone number (Settings/Phone/Call Forwarding) to the inbound phone number (DID) associated with the account. I only need to forward my number when I'm at home with poor cell coverage. Outside the house, I can go back to GSM.
I really appreciate the quick and informative replies from Otto Pylot and Avedis53. Thanks guys!
09-08-2013 08:08:31 PM
Sorry to hear we couldn't help you figure it out. I think the reason Cicso/AT&T designed the MicroCell to be so locked down was for security. There has been a proof-of-concept crack on Verizon's femtocell (nothing published so far on the MicroCell) so it appears that tight security was a priority for AT&T. Problem solving for the MicroCell should be handled properly by support but it appears that adequate training is lacking in a lot of instances. That's what prompted me to put together the MicroCell Technical Guide and post it here on the forum to hopefully help where support failed.
09-08-2013 08:32:58 PM
Otto, you put together a really great guide. I'm sure many people have found it helpful.
One last thought, for the new product team at AT&T, is to rethink whether the Microcell still has value in the evolving market of smartphones. What, after all, is the purpose of the Mcell? Why couldn't the phone just talk directly to the AT&T backend servers using voip over wifi? Get the MCell out of the middle. Would require cooperation from IOS and Android, but would be a lot less error prone. Just a thought.
09-08-2013 09:11:19 PM
VoIP using WiFi would solve issues for some but who knows what the marketeers at AT&T are thinking? I'd like to see a MicroCell that is 4G/LTE capable but that would require upgraded hardware so we'll just have to wait and see what the future holds for the MicroCell (if any).
09-09-2013 08:38:37 AM
I too share your lament about the lack of a webpage-based diagnostic interface for the Mcell. AT&T's mindset towards customers having knowledge regarding Mcell diagnostics is one of "the less you know the better".
I do know that the Mcell generates error codes that are accessable to AT&T tech support people above a certain level, as I have dealt with them while troubleshooting my Mcell and the tech stated he was seeing a certain error code that my Mcell was posting when he polled it.
It would seem to me that user access to that information would be helpful to a degree when troubleshooting Mcell problems and could even result in less calls to technical support if that information helped a user find the solution to their problem on their own.
I would surmise that while most of the problems with the Mcell stem from the wide variability in the users network hardware and how it is interconnected, some of the difficulty in getting help from AT&T when a Mcell user has a problem is the fact that AT&T doesn't make the Mcell, Cisco does. Therefore, I'm assuming that the vast majority of technical expertise concerning the Mcell resides at Cisco, not AT&T. Perhaps better technical training would make customer support more robust, but as it stands now, a person usually has better luck finding help on this forum than calling AT&T, at least when dealing with Tier One tech support people who simply are reading off a script and having a person repeat things they've already tried.
Perhaps the next generation of femtocells will be more adaptable in dealing with the variety of networking that customers have. I too would like to see 4G/LTE capability in that next generation. In addition, I'd like to see a Mcell that has wireless capability so that it can be placed anywhere, not just within hard-wire distance of a router. I don't think that would cost much more. Heck, I even have WiFi built into my $120 Panasonic 3D BluRay player so adding a WiFi chip can't be that expensive.
Good luck with your VOIP workaround!