my gateway has gone out 3 times so far

my xfi complete gateway has gone out 3 times now but when i unplug it then  plug it back in the internet comes back on.. it seems to be happening only around 4pm to 6 pm... im very skeptical on the tech company's but i would like to think it just the equipment.. im pretty loyal to xfinity and have been for 5 years now and never had one late payment.. and i pay the most i can pay... its not about the money its about reliability.. i have cameras and a security system... im prettty quit as long as my internet work theres now problems... and ive been with xfinity for so long that i dont want to start all over with a new company... i would also like to metion after the gateway went out twice i callled xfinity and they said there was no technical issues... i would like to know if i just need a new gateway or what i should do to to insure reliability