Downloads routinely fail to complete

Hello,

For whatever reason about 6 times out of 10 I am unable to successfully complete downloading a files that is larger than 200MB. At times what will happen is that I check the status of the download, I see that safari no longer shows the download speed and the status of the file size stops increasing and the download is essentially frozen in place. Other times I will see a curved arrow in an orange circle letting me know the download has failed and letting me know I can restart the download, when I see the curved arrow it is accompanied with the following message "the network connection was lost". The weird thing is that at the same time of the download i am watching Netflix instant and browsing other sites, everything loads fine and i never appear to lose connection and the wifi signal in the menu bar shows a strong signal and that i am currently connected to the internet.

When I try to download in Firefox, the download again freezes and then I am forced to download files using an older macbook pro running Snow Leopard and while using Snow Leopard I am able to complete the download. Any idea what I can do to prevent downloads from failing when all signs point to that I am connected to the internet?

Thanks in advance for your help.