Device not online (mender server not detect my device) since 2024-05-20

Dear members,

My registered device not online since 2024-05-20.
device power on some times, however, mender server not detect my device.
no change my firmware, software…

I noticed that server maintenace had done around 2024-05-20.
Any effect that ?

Do you have any information ?
Any advice would be highly appreciated.