Failure to restore iPhone 6s from backup through iTunes

Trying to restore iPhone 6s from backup on iMac on iTunes after restoring to 'factory settings'... Then I get this message on my iMac

Tried 2 different cables and different usb ports as well, I use the network cable directly from my broadband modem...

Initially it seemed as if the 'restored' iPhone 6S is current software-wise, but the backup version iPhone 6S does not have current software.

iTunes is not the latest version. (Mojave 10.14.6) But the 'restored' phone's software is now newer than the iTunes?

Might this be a conflict?

Although it did successfully restore a February 2019 backup version, but cannot restore the latest backup version from 2 days ago... Keep on giving me the 'iPhone was disconnected' message...

All this happened after trying to do a software update on the iPhone through iTunes, this crashed and the iPhone was useless - not starting up.

Then I tried to restore the iPhone to just be able to use it. Got these messages:

Eventually I got the iPhone restored through my wife's old Macbook Air. But now I am not able to get it restored to the latest backup from my iTunes. It did weirdly enough restore a backup from Feb 2019 but repeatedly fails to restore the latest backup...