Netgear Nighthawk X6 R8000 Latency and Packet Loss issues

Thanks for the response.

Current firmware version is V1.0.4.76_10.1.82, but it's occurred with multiple firmware versions over the last couple years.

I don't have the model of the modem with me, but I can say it is most certainly a pure modem.  I believe the modem is fine as the issue does not occur with any other device that is connected to it directly.

QOS and Traffic Metering are turned off by default.  I don't recall ever turning any of the additional features on (including the security suite) prior to the factory reset.  I can say with certainty none of the features disabled by default are have been enabled since the last factory reset.

I feel confident that the "highly variable download speeds" (upload is fine, consistent at 24mbps) have everything to do with my network.  There is packet loss pinging the router itself and latency spikes when pinging the second hop of a tracert.  The issues do not repeat for any device hardwired directly to the modem, and the issue began when I first installed this router though not to the extreme they are now.