Hard disk 3 keep dropping from the RAID array

Hello,

My ReadyNAS RN104 was populated by 4 2TB WD Green 5400 RPM hard disks. They were in RAID5. Then Hard disk 3 kept dropping from the RAID array. It would always resync back without any intervention. This happed a total of 4 times. After the 4th time, I thought that the hard disk might be bad so I replaced hard disk 3 with a brand new Toshiba 2TB drive model HDWT720. The volume resynced without problem but now it has again dropped off from the array. I need some help to diagnose what else could be the problem. Obviously, the hard disk doesn't seem to be the problem. Logs are attached.

Jan 27, 2022 11:34:30 AM	Volume: Resyncing started for Volume data.
Jan 27, 2022 11:34:19 AM	Disk: Disk Model:TOSHIBA HDWT720 Serial:Z051S08PSC7H was added to Channel 3 of the head unit.
Jan 27, 2022 11:27:38 AM	Volume: Volume data health changed from Redundant to Degraded.
Jan 27, 2022 11:27:26 AM	Disk: Disk Model:TOSHIBA HDWT720 Serial:Z051S08PSC7H was removed from Channel 3 of the head unit.
Jan 24, 2022 12:13:08 AM	Disk: Disk in channel 3 (Internal) changed state from RESYNC to ONLINE.
Jan 24, 2022 12:13:06 AM	Volume: Volume data health changed from Degraded to Redundant.
Jan 24, 2022 12:13:02 AM	Volume: Volume data is resynced.
Jan 23, 2022 01:00:36 AM	Volume: Volume data is Degraded.
Jan 23, 2022 12:48:58 AM	System: Alert configuration was saved.
Jan 23, 2022 12:48:48 AM	System: Alert configuration was saved.
Jan 23, 2022 12:48:37 AM	System: Alert configuration was saved.
Jan 23, 2022 12:47:42 AM	System: Successfully sent alert message.
Jan 23, 2022 12:47:24 AM	System: Alert settings are updated.
Jan 23, 2022 12:47:22 AM	System: Alert contact information was saved.
Jan 23, 2022 12:46:37 AM	System: Alert settings are updated.
Jan 23, 2022 12:46:36 AM	System: Alert contact information was saved.