Cellular interface is flapping

The customer complains that the cellular interface is flapping between UP and down

The logs below:

1. Asking for diagnostic information.

2. Asked for log.log and log.dblg files

* We’ve checked the configuration, and the customer configured these commands below that triggers the modem recovery when the NQA fails. Also, the device will search the PLMN again when the number of consecutive 3G or LTE link detection failures reaches the maximum value.

modem auto-recovery track nqa test 1 probe-cycle 1

modem auto-recovery track action plmn-search fail-times 1

Considering all these aspects, we’ve checked the NQA configuration and it is not correct, so the NQA will not succeed, that will cause modem recovery.

The frequency value in the NQA configuration for ICMP test must be larger than the product of interval and probe-count. In your case, since the probe count is 15 and the default value of the interval is 4 seconds, the frequency should be bigger, not 1.

Our recommendation is to use a smaller value for the probe count (like 3 or 4) and to set a bigger value for the frequency (frequency > interval X probe count).