Model: ATL 5G LTE16
Firmware: 7.20.7 and 7.21.x
Description:
I am reporting a consistent issue with carrier aggregation on my ATL 5G LTE16. Under normal conditions, the router aggregates 5 bands:
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Primary: B1 (LTE)
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Secondary: B3 (LTE) + B20 (LTE) + N78 (5G) + N38 (5G)
Every night at approximately 1:00 AM, my ISP disables bands B1 and N78 for power saving. The router correctly switches to B3 as primary and aggregates the remaining active bands.
The Issue:
When the ISP restores the B1 band at around 8:00 AM, the router completely ignores it. Even when running the /interface lte cell-monitor, the B1 band (which is definitely active) does not appear in the list, as if it were being intentionally filtered out or ignored by the system.
I have already tried to limit the allowed bands specifically to the ones I use, but this did not solve the problem.
Workaround:
The only way to make the B1 band "visible" and aggregate it again (other than a reboot) is to force a cell lock via AT command:
/interface lte at-chat lte1 input="AT+qnwlock=\"common/4G\",3,100,xxx,1650,xxx,6200,xxx"
As soon as the command is executed, the router "magically" detects B1 again and performance returns to normal.
I have implemented a scheduled script to automate this cell lock every morning. However, this causes a connection drop for several seconds and results in a new IP assignment from the ISP, which is not ideal.
Questions:
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Can this be considered a firmware bug in the modem's cell selection/scanning logic?
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Is there a "softer" way to trigger a full band rescan without forcing a cell lock or interrupting the current connection?