Combo modem router

Thanks much for any suggestions you can provide. I only have a basic knowledge about technology. We have a new top end laptop, 2 iPhones, 4 HD TV’s and a new 
Samsung Smart TV. Comcast provides their digital box & Technicolor TC8305T combo modem/router. They are 30 ft from Samsung and 50 ft from laptop.
Two issues we need help with: 1.) we constantly get dropped on Netflix with “not connected to the Internet” and 2.) our brand new laptop is very slow to connect to the Internet.  I think these are my options: 1.) get my own new combo m/r and keep the digital box we currently have…but which m/r will help us given our problems? 2.) keep the Comcast Technicolor m/r and simply get an extender…but which one? or 3.) get the Xfinity X1 Operating System that pairs their new digital system with some type combo m/r.  
Open to any help/suggestions. Regards, Jay Dingee