TimeMachine Backup no longer working

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My iMac ( Mac OS Monterey 12.7.6) has automatically backed up for years, however it stopped doing so on February 24, this seems to coincide with a automatic Firmware update to the WD Myclound ( Now 5.30.103 ). I had tried to back up now via TimeMachine and it starts with message ‘preparing backup’ then after a short period ‘Stopping’. The WDMyCloud disc is Healthy with 422 Gbyte free.