iPhone restore fails

Hi,

My iPhone 13 mini fails to restore a backup done with iOS26.0.1 to iOS26.1. Since the iPhone had been quite full I suspect a small increase of system size of iOS26.1 compared with iOS26.0.1 to be responsible for the fail. How can I get iOS26.0.1 back on my now blank iPhone though it is capable of installing the newer iOS 26.1?

There is no specific error message, just a disconnect right before I would expect it to finish.

Thanks for any help.

Joe.