Computer sleeps and kills download.

Update:

I tried a download using a CLI of "caffeinate" and the download was not interrupted so it seems that solves my problem.

Oh I wish it would be that simple! My Energy Saver does NOT have a slider for "Sleep"; sadly it only has a slider for "Turn display off". If you know of a terminal command to accomplish the equivalent I would gladly do that!

EDIT: In my Energy Saver window "Prevent computer from sleeping automatically when the display is off" is clicked on, (its default), so unless I accidentally unclicked it the sleep should not have occurred. Since your image of Energy Saver showed a "Never" sleep option I am assuming there must be a terminal command to accomplish "Never". I am hoping someone has such a command handy.

Thanks for your input.

Good suggestions. I will do the SMC reset at the end of tonight's session. In Energy Saver I restored defaults then set to "Prevent sleeping with display off" and "Wake for Network access". Fairly certain the OS took the settings because it "nagged" me about power usage. I also did a quick search and found references to the command line command: "caffeinate" which is just a process that occasionally does something to insure not going to sleep. I will try that for my next download session. In addition I appreciate the information about the Hot Corners, which I did not know about.

While I can not categorically state that the problem has been solved til I do another extended download I feel that all of the above suggestions and the caffeinate ploy should do the trick.

Thanks for all the information.