MC200LP-AT Carrier Reject / DHCP Failed

[aidwilli]

Hi,

I just bought a MC200LP-AT, a CBA750B, and a 600-3800MHz LPDA Yagi Radome 9dBi-11dBi Cellular Directional Antenna from thewirelesshaven. I'm using a AT&T data sim in the modem. The sim provider has instructed me to leave the APN blank as they do not use an APN for their service. The modem firmware version is 3.5.20.3 and the router firmware version is v6.2.3 .

I set up the yagi to the modem and I get about 75% signal according to the modem. The router is not set in IP passthrough mode. I'm connecting my PC to the router with an ethernet cable to the lan port on the router.


I have only changed the following settings in the WAN Interface Profile:
Modem Connection Mode: Force LTE (I did this because it gets better signal when I do it - problem persists with it on /off)
Network Selection Mode: Home Only (this will cause the error to change from "Carrier Reject" to "DHCP Failed:Client Reported Failure")
Access Point Name : Default Override (in the text box below this I leave the field blank. Following the suggestion of the sim provider, I have tried a blank space, an asterix, and "U+0020"

The sim provider thinks it is an APN issue. I noticed that there are APN profiles that the user can modify and that the last of these, profile 16, is not changeable. On the status page, the router will list the modem's current apn as a blank space as it is saved. On the cellular network subsection of the status- internet- connections page, the profile 1 is in boldface and there is also profile 16 listed as BroadbandAuto.APN.

Could this be causing the issue? Do I need to revert to an older firmware in which I can modify this auto apn thing?
What is up with the error changing from Carrier Reject to DHCP Failed when I change the network selection mode?

Please let me know if I can provide any more information. Thanks

I have also tried connecting to the CBA750B through another router running DDWRT. I can access the cba750b on the local network through the other router but the same problems persist.

[aidwilli]

So I tried a few more things:
I deleted the profile 16 apn by using AT command AT+CGDCONT=16,"","IPV4V6"
That didn't work.
Then I tried removing the external antenna and going to the base of a cell tower. Got good signal but still carrier reject.

When I do AT!GSTATUS? it lists tx power as 0 . I'm grasping at straws here. There is another modem on the way and i'll be able to test if this is an issue with the sim card or the modem.

[aidwilli]

I tried the sim in another Hotspot device and it worked fine. It's an att enterprise data plan sim. I noticed the Hotspot device was on 3g so I tried forcing the mc200lp-at to connect in 3g only. Still carrier reject.

[Didneywhorl]

It might just be that the firmware on the modem doesn't know how to deal with the APN your using, or lack of APN

You may want to use the LP6.

[aidwilli]

So I got a loaner mc400lp6 today.

It came with a couple of cradlepoint antennas. I plugged it into the cba750b with the same sim card and it works. Gives 82%RSSI with the cradlepoint antennas. The only thing is that the download speed is only ~1mbps according to speedtest. This is slower than the Telenor 4g hockey puck that the sim provider lent me to test the sim. It was stuck on 3g and getting about 3mbps down.

I tried installing the yagi to the mc400lp6 and it went to carrier reject. I started to wonder if it was the yagi or the lmr-400 cable that was causing the issue with the mc200lp (even though i tried to rule that out by going to the cell tower and not using antennas). I put the antennas on the mc200 and it still failed but it gave different failure messages.

When I tried the yagi on the mc400lp6, I put it on the main antenna jack and disabled the aux antenna in the firmware. This caused carrier reject. Then I replaced the yagi with a cradlepoint antenna and it failed again- though it showed 75% rssi. It seems the mc400lp6 only connects with both antennas of installed.

Do I need to use two yagi antennas with this modem?

Am I using the wrong type of antenna? I'm using: 600-3800MHz LPDA Yagi Radome 9dBi-11dBi Cellular Directional Antenna

Thanks

[aidwilli]

Derp figured out why the yagi wasn't working. My lmr-400 cable is rp.

[aidwilli]

It might just be that the firmware on the modem doesn't know how to deal with the APN your using, or lack of APN

You may want to use the LP6.

I think you're right

[Didneywhorl]

Oh man, RP cables will throw you!

You get it figured out now?

[aidwilli]

Oh man, RP cables will throw you! You get it figured out now?

Yeah, I did. Thanks for the help.

That LMR-400 cable that threw me was an old one from a wifi antenna I had. I got some new coax and we're good now.

I am having another issue, though. When I bought my stuff, I thought I had line of sight to the cell tower. Well, I do but it's to a verizon tower and the ATT tower I want to be on is actually over a hill and through woods. With the two wideband LPDA Yagi antennas, I get bands 2, 4, 12, 14, and 30. The MC400LP6 wants to connect to B2 all the time and I see it doing CA with B12 but it only lasts a few seconds when it comes on (seeing this in the cradlepoint firmware).

I am trying to get the modem to just connect to band 12 for stability.
On B2, I get the following signal stats:
!GSTATUS:
Current Time: 203 Temperature: 9
Reset Counter: 1 Mode: ONLINE
System mode: LTE PS state: Attached
LTE band: B2 LTE bw: 15 MHz
LTE Rx chan: 675 LTE Tx chan: 18675
LTE CA state: INACTIVE LTE Scell band:B12
LTE Scell bw:5 MHz LTE Scell chan:5145
EMM state: Registered Normal Service
RRC state: RRC Connected
IMS reg state: No Srv

PCC RxM RSSI: -79 RSRP (dBm): -113
PCC RxD RSSI: -82 RSRP (dBm): -118
SCC RxM RSSI: -77 RSRP (dBm): -106
SCC RxD RSSI: -75 RSRP (dBm): -105
Tx Power: -- TAC: 1701 (5889)
RSRQ (dB): -14.3 Cell ID: 05612D09 (90254601)
SINR (dB): 6.2

Not great signal strength but the RSRQ is not bad because I'm in such a low noise area.
I'd like to get the modem to connect to B12 because I'm sure the signal will be better. I have the antennas set at ~16.875" apart which should be about 1 wavelength at 700mhz. When I try to set the modem to band 12, this is what I do.

AT!ENTERCND="A710"
AT!BAND=11,"B12",0,800
AT!BAND=11

Then I try to do AT!RESET but the modem will disconnect me from the terminal i'm in (whether it be in cradlepoint firmware or in putty) and will seemingly reset itself. When it comes back to life, it will be on B2 still.

AT!BAND? returns:
Index, Name, GW Band Mask L Band Mask TDS Band Mask
00, All bands, 0002000007C00000 00000100330818DF 0000000000000000

Any idea what is going wrong?

[aidwilli]

for clarity, it will not let me issue the AT!RESET command. I can't type it in fast enough before the modem resets itself

[Didneywhorl]

You say your in a low noise area but your SINR says otherwise. 6.2 SINR is pretty bad. Not the worst, but not good at all.

See if you can watch the AT command stream, you'll have to look up how I cannot recall (if possible on the CP router) and see if the router is resetting the band mask on reboot.