Mycloudmirror and MBP 2016 - Timemachine issues

Hi
my MBP has been backing up to my Mycloud Mirror (via home wifi network) reliably for years - since ~mar 2017. Back in sept 2020 I updated to Mojave 10.14.6. Sometime after that, but maybe months, I began getting time machine alerts ‘backup failed - create new backup’. A few weeks ago, I got a prompt saying my HD could not be found, so I had to rename it. Airport is up to date but currently shows only ‘extreme’ (greenlight) and ‘internet’ (greenlight). (?)

Sad to see my drive is now ‘legacy’. I tried to update WD firmware but I’m confused, I don’t want to run WD’s os5, I just want to use the drive as a time machine backup. I see one thread pointing at Sophos. I run Sophos. Airport is up to date (updates automatically). Any suggestions much appreciated. !