Basically, If other Wi-Fi sources such as neighboring wireless access points are using the same wireless channel, this may cause intermittent connectivity issues, even if the competing signal is relatively weak. Changing the wireless channel within the  gateway can improve connectivity.  After changing WIFI channel as recommended on the link restart the modem then i would request you to monitor the connection for next 24hrs. please follow the steps mentioned on the below article to change the WIFI channel

http://arris.force.com/consumers/articles/General_FAQs/G34-G36-Changing-the-Wi-Fi-Channel

I have tried this solution, and then I spent over an hour with technical support to no avail. The 2.4 ghz keeps dropping connectivity.

This is my second Arris Surfboard product, btw. The first, Surfboad G36 didn’t work at all. I sent that back after lots of time with technical support, and got this G34 instead. I’m very frustrated by this whole experience .

I’m located in a rural community. Congested channels are not likely?

Could you let me know the speed plan opted with your internet service provider.

• Up to 500 Mbps download / 10 Mbps upload

I suggest you to try with this troubleshoot steps, let us know whether any changes on the modem’s behavior.

Launch a browser> enter in the address box as 192.168.0.1>login with your credentials.

Gateway>troubleshooting>restart or restore>Wi-Fi restart or restore.

After trying the Gateway>troubleshooting>restart or restore>Wi-Fi restart or restore are you able to connect to 2.4GHz and 5GHz now?

If still unable to connect to the 2.4 and 5GHz try checking cable signals also

http://arris.force.com/consumers/articles/General_FAQs/G34-G36-Cable-Signal-Levels