XR500 Causing Latency & Packet Loss

I did as you said. At first everything was much better. Now I'm getting massive lag spikes and packet loss:

https://imgur.com/Dlfq6TB

Could using my PC's MAC address as the router's MAC address be causing some sort of issue with my ISP? Should I reset the router, so that it's showing it's own MAC address, and then call my ISP to tell them recognize the router as THE device connected to the Arris cable modem?

First and foremost, I must apologize. Wish I could edit the thread Subject header, because it's false.

TL;DR: Issue was make/model of cable modem. Solved by getting another make/model.

First thing I did was change out the modem at the ISP's office, but was told none other than the Arris is available.

Its latency profile looked exactly the same as before, even after updating the firmware, which my ISP pushed to the modem while on the phone with them.

What got me on the path to the solution was Netduma-Fraser's statement earlier:

"Well for a start your base connection is spiking on its own anyway so that is an issue, the XR500 will not be able to prevent that."

"Spiking on its own, hmmm interesting," I thought.

So I connected my PC to directly to the Arris cable modem, and ran PingPlotter on it via its Default Gateway address. Here are the results:

https://imgur.com/E3ivrdJ

"Wow," I thought, "all those spikes are getting added on to my traffic right out of the gate; no wonder I'm having issues."

So I researched this for longer than I'd like to admit, and finally stumbled on articles/posts written about some lag issue, at regular intervals when plotting latency over time, with Intel Puma 6 chipsets in certain modems, and not just certain Arris modems. A lot of ticked off gamers out there right now over this. Apparently, the issue can't be resolved through a firmware update. There are lists of many modem makes/models using this chip set, not only Arris.

So I called my ISP and asked the tech rep if we're allowed to buy and use our own cable modem, and he said, "yes, as long as it's on the list of approved modems on our website." So I looked that list up, and there were a number them on it. Some that may also have the Puma chipset, but others that don't, such as the Netgear CM600, which has a BroadCom chipset.

The CM600 was available locally, so I bought one for $100.

Got home, hooked it up, and called my ISP who walked me through the activation process. First thing I did was run PingPlotter on the Default Gateway with only my PC connected to the CM600. Sorry I didn't snap a screen cap of that one (and not going to interrupt my wife's Netflix to do it now), but it was beautiful (talking on the order of 1 ms average latency).

Here are my PingPlotter results for wired PC pinging Google via the XR500 and the CM600 with a bunch of wirelessly connected to it on default QOS settings. These two Netgear devices really like each other:

https://imgur.com/jpM73LL

Thanks, Netduma-Fraser for setting me on the right track. You guys are great.

P.S. Really feel bad for people who either don't know they're being affected by this issue or can't afford to change out their Puma 6 chipset cable modems for something else. "Why didn't that click register!" "Why does this game keep kicking me!" "Why is everybody warping!"