Yesterday I purchased the PC DVD version and installed it and started the downloads.
I downloaded about half the files then paused the download and turned off the computer for the night.

Today I resume the download but it has started from the beginning. (I suspect a patch update caused this).

How do I pause and resume the download without going back to the start of the download each day??

I do not have a fast internet connection so I want to download the game over the next few days but still pause the download
at the end of each day and turn the computer and internet connection off at night.

I even do not pause the downloads, I just shut PC down and the download has allways resumed. Of course, I don't know about Fallout 4, but shouldn't that be the same case? I have left my PC running overnight for downloading.

Thanks. I tested restarting the computer and steam. It works ok. I think a patch update overnight caused a problem.

For anyone interested - My solution is to put the computer (desktop running windows 10) into hybernation. This means that steam will not be shutdown. I can then turn off the computer and when I restart - steam will be running and can resume the download.