Unable to update IOS through Itunes on windows

I've been trying to update to the current IOS update (14.6) through itunes. It recognizes that there's a new update and asks me if I want to update to the current IOS. Itunes goes through the normal procedure though. It does download, however I always get an error code that even Apple does not have a known code/solution for it; the error message is "The iPhone "iPhone" could not be updated. An unknown error occurred (4000)." I've tried keeping my phone unlocked like some people have suggested. Although I've tried all the suggestions and none of them have worked. I tried on another computer, still the same thing. I've reinstalled Itunes multiple times. I'd rather go through Itunes on PC because it's much faster than downloading over wifi.