What is happening with 3G?
mpcookson's profile

Contributor

 • 

2 Messages

Sunday, March 8th, 2015 3:40 PM

DPH-154 fails to get DHCP IP from router

I bought the DPH-154 yesterday and got it home, plugged it in and started the configuration, but the status webpage never got past "Power Up Pending", even after leaving it over night.

 

Checking the DHCP server on the Cisco LRT214 (router with VPN tunneling so that I can access my home network when I'm on the road) shows that it's never received an IP request from the DPH-154's MAC address (even though everything else on my network has a DHCP address). It's MAC address never shows in the LRT214's DHCP logs. I can't find it in the arp table after I ping every IP address in my network, so this confirms that the DPH-154 hasn't received a DHCP address.

 

When I have it plugged into my switch (TP-LINK TL-SG2424) I get the Ethernet light on the DPH-154 to light up, but when it's plugged directly into the LRT214 it won't light up, though the LRT214 knows it's there, saying it's connected at 10Mbit.  If I then reboot the LRT214 the Ethernet light on the DPH-154 will come up at 100Mbit, but it still doesn't get a DHCP address.

 

I've tried moving the DHCP server functionality to my AirPort Extreme but that caused headaches and it didn't work. I tried moving the DHCP server functionality to my AirPort Express, again, headaches and it didn't work. I moved the DHCP server functionality to my Linksys N750 (or EA-3500 depending on if you believe the box it came in or the printing on the device itself) and it was finally seen and apparently got an IP address because suddenly the GPS light started to flash, went solid, and then the Network light started to flash.

 

However, the AT&T website still didn't show that the DPH-154 had made it to the Power Up Pending state. On top of that, every other device on the network stopped working. I eventually tracked this down to the fact that N750 gives out its IP address as the gateway, even if it's not (the LRT214 is still the gateway since it's plugged directly into the cable modem).

 

One last thing to try, I moved the DHCP server functionality to my Linux CentOS 6.5 box since with it I'm able to configure all DHCP options exactly as I need them to be. And with that, and a quick unplug/replug of the power to the DPH-154, the DPH-154 roared to life!

 

The AT&T website now sees the unit and I'm currently 3+ minutes into the "Location Verification" stage of the setup.

 

Looking around the web, I was able to find one other user that reports that their DPH-154 doesn't work with their Cisco router (different model) which is what got me thinking that I was never going to get it to work unless I got a different DHCP server. Luckily I have a Linux server that I could task with the job.

 

So, I hope this information helps others that might be in the same boat... It's probably your router's DHCP server, so if you have options, see if you can get rearrange your network to put one of the other devices in charge of DHCP duties, but know that it might not be easy. It might be a firewall issue (wasn't in my case), but if the GPS light never lights, then it's almost certainly a DHCP problem.

 

And as I write this, I now I have a functioning microcell (Location Verification took about 6 minutes, the whole process took less than 15 minutes, once it got a DHCP address)!

Avedis53

Professor

 • 

2.2K Messages

8 years ago

Thank you for posting your experience with your Mcell.  Your network is more complex than most and when multiple DHCP server-capable devices are connected together in a network, there can be problems with double NAT.  It sounds like that was your problem as the Mcell doesn't play well with double NAT networks.

 

You didn't say what you did when moving the Mcell to your various DHCP devices but I'm assuming that you were also putting the other DHCP devices in bridge mode and only allowing one device to carry out DHCP duties.

 

I'm glad to here you were able to troubleshoot your way out of the problem.  What you experienced can be a head scratcher when the Mcell doesn't authorize.

Contributor

 • 

2 Messages

8 years ago

There is only one device doing NAT, it's always only been the LRT214, and all the access points have always been in bridge mode (no DHCP and no NAT).

Double NAT was one of the things I thought about, but the fact that the LRT214 never gave an IP to the DPH-154 was the key point. NAT is step 2, getting an IP is step 1, and it was clear from the arp table that we weren't getting past step 1.

It's very strange that the 154 sends out a dhcp request that the 214 won't answer, but that appears to be the case. The suggestions of trying new routers are definitely valid, though expensive, if the 154 never lights up it's GPS indicator and the AT&T website never starts the activation process.

Thanks to your posts and others I stuck with trying to debug the initial connection problems, moving the 154's connection (the patch panel makes it easy to move it from the switch to the router and to other devices) and luckily I had a lot of different devices that I could test dhcp servers on. I only have one dhcp server running (only ever did), it's just a different one now. 🙂

Cheers,
Mark
Avedis53

Professor

 • 

2.2K Messages

8 years ago

Thanks for clarifying what hardware you had bridged in your network.  We have seen other routers/gateways that for some reason don't work with the Mcell.  I agree that experimenting with new routers just to get the Mcell to work is a pain.  One has to remember that the Mcell is a dumb, plug and play device that realistically can't be built to accommodate the entire family of routers/gateways that are currently available on the market.

 

We've certainly seen a number of previous posts here about Mcell/router incompatibility problems, so it's not so rare.

OttoPylot

ACE - Expert

 • 

20.2K Messages

8 years ago

I've been out of town for a couple of days so I'm just dropping in to see what's up. I'm glad the OP took the time to reason out the problem and come up with a solution. Nice job. I agree with Avedis54 that some routers just don't play well with the MicroCell and vice versa. As home networks become more complicated the likelyhood of MicroCell issues will probably become more frequent.

Not finding what you're looking for?
New to AT&T Community?
New to the AT&T Community? Start by visiting the Community How-To.
New to the AT&T Community?
Visit the Community How-To.