Download Stops and Computer Restarts

hey, guys

i dont know if its because im running on win 10 or anything like that but what happens is that i open up the epic games laucher, press start download and then it downloads just fine until about 72 percent. At that point, the rate at which it is downloading starts to fluctuate. I normaly get 10mb/s but it went down to 8 then back up then 7 and back up and so on until it got to 2 mb/s my computer promptly restarted and i cant resume the download becuase i apperently dont have the 88 gb of space it needs to download the whole thing. I dont know what is going on and i am utterly confused. Please reply if you are having similar problems or can fix this.