Download keeps failing in Safari?

I am trying to download a 300 mb file in safari through downloads. The problem is, it just keeps stopping and claims it has lost connection the the internet. The internet has been fine and I dont think this is the problem. The computer has been running whilst downloading so there is no way my mac could have disconnected from the internet to go to sleep. The problem is, that my file gets half way then I have to press reload to start it going again which seems to start the download from the beginning again. I feel like i'm stuck in a loop. The furthest it has got to is around 60% then it just stops resulting in me having to reload it again.

Is there anything I can do about this? Also when I click reload, does this start the download from the beginning again or continue from where it left off as the blue bar seems to go back to the start whenever I have to reload it?