Iphone Update Error 4010

Trying to restore my iphone 7. Using iTunes on PC. Get all the way through downloading, unpacking and beginning the restore...with the iphone screen white and the black apple. Then, when the status on the PC gets to 'Checking with Apple'...it puts up the error box and says The Iphone "xxx" could not be restored. An unknown error occured (4010).

I've tried new cables, suspending virus software and firewalls, and updating itunes. All to no avail.

Any ideas on what is causing error at this stage?