N300 C3000 Wifi Stops Working / Connecting

Hi my Cable Modem / Router N300 C-3000 has a really annoying issue where after about 10 mins it stops communicating with all my devices. I called the cable company who said my signal was great (TWC) and tried setting fixed channel and factory resetting. Neither fixed it, when I run a speed test the download speed via wifi fluctuates from a few MBS to like 45 and the upload stays constant. After 10 minutes I can't connect at all unless I unplug and replug the router in I think the firmware is broken TWC said they cant downgrade it and its the latest version.