Hello Eigil, welcome to the community!
Thank you for the logs. From them, it appears that there is a combination of errors, I’ll list them:
2021 091 06:07:03>> Time adjustment M0: HARD RESET. This will result in a one-time time-tear.
2021 091 06:07:03>> 5.0: NTP Time (Init): NTP: 1617257222.708330393
2021 091 06:07:03>> 5.2: NTP Sync (HARD): VEL Before: 1617256859.674999952 After: 1617257221.667999983 Diff: 361.993000031
The first one is this, where it seems that the Shake loses the connection to the internet and thus loses also the connection to the time synchronisation services. Without these, the Shake does not transmit data to our servers, because it would be off-time, and the result is that you see what you are seeing on ShakeNet.
|2021 091 06:16:40>>|Data has been successfully received, fatal condition resolved.|
|2021 091 06:16:41>>|No Data has been received from the MCU in 14 read attempts.It appears the MCU is not transmitting data. This is a fatal condition and should be investigated if this condition persists!
This is the second one, and the reason why you see the gaps in the local helicorder. It indicates that every now and then there is no communication between the Shake OS and the Shake blue board/geophone sensor.
I would advise you to check all contacts between every component, check if the power supply is still working properly (the Shake needs from 5.0V to 5.2V and 2.5A), check if the Raspberry Pi board is working fine and, lastly, you can try to re-burn the microSD card or try with a completely new one, to see if the issues are caused by corrupted files.