Hi @shib, sorry for the delayed response. Regarding the “cm radio rat” command - it accepts a bitmask, and it’s slightly different than +KSRAT in that it only accepts the supported RATs, whereas you’ll see options with UMTS in the mask for +KSRAT. Does that explain the difference you’re seeing? For WP77xx, the only valid combinations for cm radio rat would be “GSM”, “LTE”, or “GSM LTE”. If you want to try to narrow down the LTE capabilities, in case you suspect a difference there, AT!SELCIOT can enable only Cat-M1 or NB-IOT, which can optimize scan times if you know you have no service in one or the other. If I’m misinterpreting the problem with pa_mrc_SetRatPreferences(), let me know and I can follow-up.
The fact that the issue seems to coincide with an unexpected W_DISABLE signal is alarming to me. In the thread you linked, the root cause of that unexpected signal wasn’t described. Are you using a mangOh platform (as in that thread), or something custom?
Do you have any custom software that might be exercising radio control APIs when coverage is lost? I’m not aware of anything specific, but I wonder if the radio could be accepting a mode that isn’t valid, leading to it becoming stuck in this state. If you can get a device in this state, you could try a series of AT!GSTATUS? to get an idea of the band’s being scanned. When in a no-service state, you’ll see periods of idle, which is a power saving mechanism if the device thinks there is no signal. But if you keep sending the command, you should see some cycling band information during the scans, in this state. Feel free to send me a log of this by attachment, and I can see if there’s any clues there.
Lastly, if there’s any reduction of variables you’re able to make to narrow down the issue, that would be good to try. For example, if this isn’t the baseline WP77 software release, it would be good to confirm whether or not it happens with that (also, which Modem release is being used?). Same for hardware, especially based on the W_DISABLE problem - if this isn’t a mangOh platform, it would be good to have a result from some reference hardware, if possible.