Horrible Latency every night 9-11pm EST

Hello All-

I'm not expecting much help here, but it's worth a shot. I've had Cox for 2 years now and they are the only ISP in my neighborhood. I work from home during the day and game at night. I typically game around 3-4 hours at night playing games like Modern Warfare and Rocket League. Almost every single night for the past 2 years I've encountered horrible latency between 9 and 11pm. This happens without fail. Sometimes it lasts longer than others, but lately it's getting start of COVID bad. I thought it was modem, so I bought a $400 nighthawk modem router. I'm connected via ethernet to my pc. I have about 18 devices connect all the time, but most of them are cameras, echos, google home minis, etc. Nothing that should be funneling data on the regular. I also pay for the gigablast internet. I've had techs crawling around my house over the past 2 years and most of them admitted it's a node/overload issue. They finally split the node in early 2021. I saw some relief, but the spikes never stopped.

Currently it's getting to the same point it was before the node split. Intense spikes for ~2hrs every night when trying to game. Its honestly unacceptable, but there is no other ISP in the area. I need a tech to come here at night and witness exactly what is happening. Support does whatever they do on their end and tell me everything is fine. I'm hoping there is something that can be done to fix this issue. I notice the signal levels are always poor when I visit my modem's page. However, during the day, there are literally 0 issues. I have taken days off and played during the day and have no spikes. Someone please help!!