Since it's a gateway, let's first isolate if the issue is wired or wireless. The best way to do this is to see if the LEDs on the front began flashing when you lose connection. If this does happen, then the issue is with the communication between your ISP (service provider) and your gateway. The most common cause for this issue is the signal levels being out of range or close to being out of range. Check out the link below for more info on signal levels. For the intermittent connection check the cable signal levels and change the Wi-Fi channels :

Follow the below links on the same:

http://arris.force.com/consumers/articles/General_FAQs/SBG7600AC2-Cable-Signal-Levels

http://arris.force.com/consumers/articles/General_FAQs/SBG7600AC2-Changing-the-Wi-Fi-Channel

Also, check on the below points: 

• Placing your gateway in the center of your house
• Don’t place it behind any electronics or appliances
• Don’t place  it too close to cordless phones (landline not cell), baby monitors, or your microwave
• Make sure it’s not behind a metal or concrete wall as the signal has a hard time going through them
• Check if the Co-axial cable is tight /has no cuts or loose ends 

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