Late replay, thank you for the updates all. I tried yet another ethernet cable and it seemed stable up until today.
In this case, when I check the router settings, the connection says "CONNECTED", but none of the clients have internet access. It seems a quick way to fix it is to unplug and...
My Asus RT-AC86U will consistently lose connectivity, both its lan ports and wifi. On the network map page it waill say "Internet status: Not Connected" It occurs about 2-3 times a week, seemingly randomly. I am using sonic fiber internet and it works fine if I hook up the ONT directly to my PC...