NetGear N300 connected but no internet

I am sure this has been asked several times, but I need help. I can't find exactly what I am looking for!  

Our router in the house is in the basement.  We originally had the family room there, but once my roommate's baby came, they moved upstairs.  My bedroom was an extension to the house so service on my Roku loaded TV has always been sketchy.  Constant buffering, error messages, internet loses connection constantly.  

I caved in and bought this extender and it arrived yesterday.  I followd the setup via WPS.  I am not techy savvy at all, so I have no idea what WEP is...  I brought the router upstairs, plugged it in to an outlet closest to my room.  I turned on my TV, searched available networks and found the _EXT.  I connected and had 4 bars immediately (Previously just one!).  I was so stoked.  I was able to log into Google movies and finish watching a movie; logged into Sling after and everything loaded incredibly fast and watched several shows.  Around 5:30, I left my bedroom to make dinner.  Came back to the room around 8:30, turned the TV back on, still had 4 bars.  Turned on Sling and was watching a movie.  Within about 12 minutes... I got the dreaded buffer.  Then, "we're sorry, the app is not responding, please try again."  4 bars showing the entire time.  I try Hulu, Netflix, Pandora.  Almost instantly "no internet connection detected".  I check the extender and all green buttons still.  I factory reset it, restarted my TV,  went downstairs and connected via WPS again.  Came up, plugged it back in, TV says my signal is Excellent.  Try to log into Sling again and boom.  No internet connection.  Again, I am not sure if I should connect via the computer?  I am not good with this WEP/WPS stuff.  I obviously have a key/password to enter when I connect to the network.  I factory reset it 2x and still can't connect.  It almost reminds of when I tried to hotspot from my phone to my TV awhile ago and said I had excellent signal but nothing would load.  

I need some advice, please.  I was so frustrated that I almost threw it out the window for a car to run over.  Life is crazy hectic in the house and everyone works and we always forget to call to have the router moved upstairs.  Originally Comcast said the basement was best becasue that's where we were spending majority of our time.  I just want to lay in bed and watch a few shows before bed!  

Why would it just stop working?  I was so excited I had signal and no buffers and clear picture, not pixelated.  It is not even a day old and I hate it already!!  :)  

Any insight, suggestions, help, comments appreciated.  

Thank you.