I believe I may have found a bug in 378.52_2. I have been going crazy for about 6 weeks or so. Every so often my WAN connection would tank. All would appear to be in order, the router would allow me to access it and would report a working WAN connection (IP Address, gateway & DNS servers listed on Network Map>>>Wan Status). However, most sites were inaccessible and the ones that did render were cached versions. If I cleared the browser cache then nothing would render at all.
So, after about a dozen factory resets, an average of 2 each week for six weeks, I decided to try and ascertain the problem and I think I have found it, Traffic Analyzer. I have now successfully reproduced the problem and fixed it 3 times after meticulously activating features one at a time and rebooting. First, it only happens when Traffic Analyzer is switched to "on" and after the router has been rebooted. It happens on IE, Chrome, Firefox and Pale Moon. I have a script in place using JFFS to automatically reboot my router at 05:15 each day. So anytime I would try activating Traffic Analyzer the following day the WAN connection would be broken, seemingly on its own.
So, as soon as I had switched Traffic Analyzer on and rebooted the issue instantly appeared upon the router coming back up. Turn off Traffic Analyzer and reboot (rebooting client as well) and guess what? You got it, the problem would be gone. I have now reproduced the issue twice after initially discovering its apparent cause so I am fairly confident that something untowards is occurring. In thinking about this issue it started as soon as Merlin added the TA feature for the AC87x platform, IIRC.
My ISP is COX, I have an Arris/Moto SB6183 modem, all new cabling from the tap on the street all the way to the modem (took a 2 man crew about 3 minutes to run RG-11 from the tap on the street to the side of my house) and a Cat6 cable running between the modem and router.