internet problems

We recently got an email saying we could up our internet speeds if we upgraded our Xfinity gateway from the XB6 to the XB8. Ever since then, we have had the absolute worst internet experience we have ever had in our entire lives. The problem is, it will be working for hours and hours, even days, and then randomly will go down with absolutely no connection. It'll go from a solid white light, to a solid orange light, to a blinking orange light, then back to white over and over and over again. Since we have encountered these problems, I personally have talked to about 10 different agents AND have had 2 tech visits and the issue STILL remains. I have also personally changed the coax cable, changed spots for the router and moved it, I have done everything and I have no idea what to do anymore. Might switch from Xfinity to another company as people keep telling me it is resolved and it is surely not. I have never experienced this bad of a problem with internet in my entire life and it is a shame. Any help would be GREATLY appreciated. 

p.s. Also recently, when the internet does work with devices that use ethernet, it is fine but, devices that use WiFi do not work :(