1st question to be asked is are you using ABP or OTAA? How is device configured? Have you addressed any FCount issues?
When you say
Do you mean no data arriving at your device Console or in end application (via an Integration) or can you see that device is not physically sending an RF Message - nothing seen in e.g. a GW console window that is able to hear the device if it does transmit.
Most devices are ‘time’ unaware other than relative time wrt their own transmissions (RX1/RX2 windows etc. depending on how configured. Dont know this device personally and havent looked at its operational details but often after
You find the FCount expected in the LNS is not that being sent by a (reset?) device that has had a battery change…as LNS sees lower FCount as potential replay attack and drops packets! try resetting session/fcount in device console window, perhaps?