unknown error occurred (1667)

I'm trying to update my iPhone 6S to newer s/w version, am at iOS 14.8.1. Thought i would get 14.8.2 but s/w wants to do 15.1 which I'm fine with.

Download & load would not work. Got download only to work, uncertain what version, but now when I press Update button i get the msg: "There was a problem downloading the software for the iPhone .... An unknown error occurred (1667).

Wondering if I need to delete the download and try again, but don't know how to delete a download.

Uncertain how to proceed.