Why do uplink messages stops some time

Some times I don’t receive the uplink messages from server(mqtt).I only receive the downlink messages. To receive uplink messages I have to reboot it again. Can anybody help please.
My uplink and downlink messages are attached below.

Uplink Message
applicationID: ‘9’, applicationName: ‘ThirdDeviceTest’, deviceName: ‘LevelSensorV5’, devEUI: ‘cSBCsdaA5rQ=’, rxInfo: [], txInfo: { frequency: 918000000, modulation: ‘LORA’, loRaModulationInfo: { bandwidth: 125, spreadingFactor: 12, codeRate: ‘4/5’, polarizationInversion: false } }, adr: true, dr: 0, fCnt: 0, fPort: 1, data: ‘I1RMMDU6MzE0NCwwDQo=’, objectJSON: ‘’, tags: {}, confirmedUplink: true, devAddr: ‘Ac0HfQ==’, publishedAt: ‘2023-09-01T07:00:23.921438940Z’, deviceProfileID: ‘01f7c870-f533-4982-a530-fc2be5706072’, deviceProfileName: ‘WaterLevelTest’ }
{ confirmed: true, fCnt: 0, fPort: 1, data: ‘DOWN’ }. \