I've been experience significant speed drops in the evening. Great speeds in the early morning (near my gigabit download speeds). Have the PW8 modem (for free during a two year deal). Cox's own wi...
So here is my data. Thursday evening (before this plot ) was bad. Friday evening a dip, not advertised speeds, but still fine for things. Saturday at noon - download bandwidth plummeted. Around 3 PM yesterday, fine again. Then about 8 PM, downloads were bad again. Right, now all is good. Note - I have published an app with the live data (speed test run at the top of the hour, with a couple on the half hour in the evenings. I can run by hand and add data points too.).
The app will let you download the data as well.
I will send a link to the Cox help email. Notice that the upload bandwidth is mostly fine (I have the 100 Mbps upload speed) , just the downloads go to heck. I'm on a PW8 modem, but all these tests are run directly connected to the PW8 via ethernet on a machine with wifi turned off.
When it is bad, the cox Wifi app speedtest reports the same really bad numbers, and asks helpfully to reboot my modem (which does not help).
I'm also experiencing the exact same issue you are describing here, but I have been tearing my google wifi system apart and rebuilding it over and over each time I'm seeing this happen and it's driving me insane!