Did anyone figure out how to hold carrier aggregation with AT&T?

[Dlkelley713]

Hey Folks,
Newbie here. I have a WG1608 router with WiFix GoldenOrb_2022-03-23 and EM160R-GL modem on 07 firmware. I read through a very long thread about this subject, but I never saw any closure. I couldn't figure out so far how to determine what CA bands are being used, but my symptoms suggest that CA is being fully deployed when I first start/ reboot my router, but after a short time my speeds drop and never rebound unless I reboot. Based on that previous thread, this is common behavior for AT&T.

Did anyone come up with an automated way to keep CA enabled on ATT? BTW, I'm happy to learn, but I'm not much of a router / modem geek yet!

Thanks for any help!
Dan

[Dlkelley713]

Thanks eskaryo,
That's very interesting. Mine was on OpenWRT when I got it and noticed the issue. I was hoping swapping to Rooter / GoldenOrb would "fix" it, but obviously it didn't.

Anyone else able to aggregate full-time with AT&T and Quectel modem? what router and modem do you use?

Thanks!
Dan

[RJ2021]

Hi Dan, I use a wg1608 with a EM160R-GL...I did have a few issues with the EM160 disconnecting, especially after aggregating...I believe Quectel did fix the problem after they issued firmware version EM160RGLAUR02A09M4G for the EM160R..I also do a daily reboot and have not had anymore issues with it after upgrading my modem.

Regards, RJ

[Dlkelley713]

Thanks RJ, I updated my firmware to version 10 this morning (from 07). I'm hopeful that things will be better!

[Dlkelley713]

I'll answer my own question in hopes that will help someone down the line (or myself if I forget). For the record, I'm using a WG1608 V4 (according to the label in the router) with an EM160r-GL modem. I'm on WIFIX / GoldenOrb 2022-3-23. Modem firmware updated to EM160RGLAUR02A10M4G.
Anyway, I was getting very sporadic results. Carrier aggregation always worked after reboot, but it would usually stop working after several hours. My speeds and ping times were all over the place. I saw pings from 40ms to 800ms. For some reason, when the modem was "struggling" with high pings and low speeds, the modem would quickly heat up... well into the 70s(c). It seemed that certain combinations of primary and aggregated bands led to the problems. I monitored which band was "primary" when things worked best. I recalled an earlier post by someone who claimed that cell lock could be used to specify a single cell, and carrier aggregation would still work with the remaining local cells. This was the ticket! I used cell lock with the band that I'd see behave the best as primary. Once it rebooted, it always connects to that cell / band, and it still gives me 4x aggregation with other bands. Even better, it doesn't seem to lose its ability to aggregate during the day. I'm pretty rural with mediocre signal, and I'm averaging over 50mps download now. While I was wrestling with heat, I added a small heat sink to the modem and fabricated the router with a blower. I was still getting into the 50s(c), but since I locked that cell, I don't think I've seen it exceed 32(c)!

Anyway, sorry for the long post, but I hope it's helpful for someone. I've learned a ton here recently by wading through old threads.

Dan

[TooTall]

I will also add something suggested on the FB group...I toyed with some scripting of periodically resetting the modem bands to mimic what is expected of true mobile devices, and this is the only way I have been able to keep CA alive on Verizon. Installed (or verified socat is installed?), and manually tested commands for a week or so while building the script. What I found was that the modem is constantly regurgitating information and sometimes mixes up AT commands sent via echo or socat. So, I had to complicate the script a little bit and make sure I'm getting an "OK" from the modem when I set the bands to 66 only, then back to the bands I want to use to CA. In order to prevent the script from running indefinitely, I give up after a certain number of tries. I want my bands set to the range specified, even if setting to 66 only didn't work, so I try the range of bands more times.
I have the below script (/etc/set_ca_bands) set up to run every 30 minutes (YRMV), and only during the hours of the day that fit our household needs.
Scheduled via the System..."Scheduled Tasks" in Luci : 8/33 8-21 * * * /etc/set_ca_bands

root@WiFiX:/etc# cat set_ca_bands

Code: Select all

#!/bin/sh

TRIES=0

while true
do
  stty -F /dev/ttyUSB2 raw -echo
  echo -e "AT+QNWPREFCFG=\"lte_band\",66" |  socat - /dev/ttyUSB2,crnl > /etc/set_band_66.log
  MODEM=$(tail -1 /etc/set_band_66.log | cut -c 1-2)
  if [ "$MODEM" = "OK" ]
  then
    break
  fi
  TRIES=$((TRIES + 1))
  if [ $TRIES -eq 3 ]
  then
    break
  fi
  sleep 2
done

sleep 3

TRIES=0

while true
do
  stty -F /dev/ttyUSB2 raw -echo
  echo -e "AT+QNWPREFCFG=\"lte_band\",2:4:5:13:66" |  socat - /dev/ttyUSB2,crnl > /etc/set_ca_bands.log
  MODEM=$(tail -1 /etc/set_ca_bands.log | cut -c 1-2)
  if [ "$MODEM" = "OK" ]
  then
    break
  fi
  TRIES=$((TRIES + 1))
  if [ $TRIES -eq 10 ]
  then
    break
  fi
  sleep 2
done

[Didneywhorl]

I made my own version that seems to work for me so far in my test. I basically just send the at command (via echo) every 5 minutes to remove a single generally unused band, or add the band back. Quectel modems handle this without dropping connection. I use the presence of a self created /tmp/ file to determine which to do. If the file exists, unlock the band, if it does not exist create the file and lock out that one band. I do this to an LTE band. It seems to keep the connection updated and refreshed ... so far at least.

Running it every five minutes without any extra code for error control allows it to run and work without overworking the processes, yet is also often enough that if it does fail, even multiple failures, it still will work over time enough to keep things refreshed. I could likely extend it to every 10-30 minutes, but so far it seems fine.

[swfl_extreme]

I believe this is the problem I’m currently having with my Quectel RM520N-GL. How do I solve it? I am currently cell locking and it does aggregate after a reboot, but within an hour it drops back to a single band.

[Didneywhorl]

It's a thing ATT does as a management protocol on the tower. You cannot overcome this, the tower is disabling it after an arbitrary timeframe on any connection that is constant. Verizon has also done it. Any form of disconnect/reconnect fixes it. You don't have to reboot the modem, only force a reconnect to the tower. There's no real good way to automate it that I know of.