a cheap option to get a better signal upstairs is place your modem / router in a large metal salad bowl. This will act to focus the radio signals upward. Imagin if you will your router sending out a signal in all directions like a ball that grows larger, all parts of the signal that go down, are waisted. By placing your modem / router in a large metal salad bowl, the waisted part of the singal is redirected upward to the upper levels of your home. I used to work for comcast as a tech and had a unrelated service call to a customs home in the same situation as you. When I went to the modem to check cable rf levels his arris modem was sitting in a large salad bowl and im like wth? He told me why and, then I went to the upper level with my hand held and had great signal, he then removed the bowl and my hand held could not even get enough signal to open a web page, I was amazed.