Mine was doing the same thing for about a week. Then two days ago I realized that I didn't have to reboot the equipment at all. Since then it's been working great.  Not sure if Arris did something or if it was Xfinity. I'm just happy I don't have to reboot 5 times a day. 

After weeks of frustration with this same issue, and unable to find an answer that worked on these message boards, I did a full gateway reset and re-install last night (a real pain for everyone and their devices).  Everything worked when I went to bed, and when I woke up it was still working.  These last 12 hours are the longest I’ve had my 5G network consistently working in about a month.

I initially tried my reset/reinstall through the Surfboard app on my phone.  It didn’t work after several tries, so I used the web-based settings page (192.168.0.1), which eventually worked after 2-3 attempts. 

For me, both the 2ghz and 5ghz have slower speeds and intermittent drops. Interestingly, the 2ghz is faster at ~50mbs down vs the 5ghz at ~15mbs. I have random ping spikes and disconnects on both.

In attempting to narrow down the issue, I’ve tried all the a/b/g/n/ac/ax settings. Specifically when we to ax, none of my devices are able to connect to the 5ghz (but still can to the 2ghz). This used to work fine, and was the reason I bought the g36 as ax is wifi 6e if I’m not mistaken. 

Before the update, I was getting 300+ mbs on 5ghz with a silky smooth connection. After, and currently, it’s borked 90% of the time.

I will try the full reset & re-install tonight and hopefully report back.

Same problem here. The 5G network disappears after some minutes. When I restart the modem it shows up for a while but disappears quickly 

UPDATE:  I’m on about day 3 after my full reset, and so far no issues.  I can’t explain WHY it worked, but so far so good.

I also tried a full reset - as in pressing and holding the tiny button in the back until it reset the whole thing. It took maybe 10 minutes and wiped all of my wireless settings… but this method also fixed everything for me! I also cannot explain why - the settings are back to defaults but all of my devices can connect and I am getting 200+ mbs on the 5ghz. Very few lag spikes.

Thanks @RyanB036! I highly recommend anyone that’s having wifi issues with the g36 take the time to do this. It’s annoying, but I’m going on 12 hours now with no issues. I’ll definitely come back to report if that changes.

Since you are experiencing with intermittent internet or the Wi-Fi network name disappears completely, I suggest you to check the firmware version on GUI web portal.

Also change the Wi-Fi channels with least congested one and monitor the performance for the next 24hours of time.

To change the channels, find the link given below:

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

And make sure that DCS interval should be 8hours.