modem network drop to 3G from LTE, but can't back to LTE network

[dailijin]

Hey,


I am using MC7354 modem with auto technology preference mode and it can work via libqmi on LTE network at the beginning, after run long time, it drop to 3G network and not back to LTE. if I reconnect the modem, it will work on LTE mode


For to trace the issue why it can't back to LTE mode, I print all cells informations per 5 seconds to check RSSI,RSRP,RSRQ etc. Before modem don't get connected, I can see all key value for LTE,WCDMA,GSM, but after it connect LTE, I only can see the key value for LTE,  and when it drop to 3G, I only can see the key value for WCDMA and can't see the key value for LTE  or other RAT(radio access technology), so I want to know  is there method via libqmi to check the key value for all RAT regardless of the modem connect or disconnect?


Based on my understand, modem should take charge of cell reselection and RAT reselection,  so I think the modem should back to LTE automatically. AM I right?


About this issue, Could you can give me some suggestions?


Thanks in advance.





--

Best Regards,
Dai,Lijin
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