Note: the Firefox security.tls.version.min supposed “work around” does not fix this problem.

Since you are experiencing with error while logging into the GUI web portal, I suggested you to try with different browser and different devices.

Also make sure that VPN is not enabled in the devices which you are trying to logging in.

Same result with multiple browsers on multiple computers . . . no VPN.

When I try to access GUI web portal using this link (or anything similar)

ARRIS window pops up and redirects to https:// secure connection

which results in this error massage

we could not verify the certificate: reason = untrusted

Now, in addition to ARRIS redirecting my GUI web portal login to a security level that my G36 DOES NOT SUPPORT . . . this $325 piece of absolute garbage is dropping our 5GHz signal.

If you are having the screen states redirect while trying to login GUI web portal, I suggest you to select proceed and continue with the page.

Its just for warning alert, it wont get misused in any way.

Also you have mentioned that intermittent internet connection on 5Ghz network, I suggest you to change the Wi-Fi channels and monitor it for next 24hours of time.

To change the Wi-Fi channels, find the steps in the below given link:

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

If you will read my first post; dead-ended right there . . . no option to continue

This is it

no option to continue

Have you tried with different browser and different devices to login the GUI web portal?

Also I suggest you to login the web portal without co-axial cable.

If you tried all these troubleshooting steps, then I suggest to factory reset the modem and try again. 

If you would read my previous posts: “Same result with multiple browsers on multiple computers . . . no VPN.”

Disconnecting the co-axial cable results in the exact same dead-end error. Factory reset and re-trying all of this nonsense results in the same dead-end error.

It looks like you are not able to access the admin portal check on the following points  on your device : 

• Fix System Date and Time
• Clear Browser Cache
• Reset Browser Configuration
• Also the causes of SSL security certificate errors check on 
• Incorrect date or time configured on your PC 
• Expired SSL certificate on the website 
• A self-designed certificate on the website server rather than from a CA
• Certificate not installed properly