Internet slows to a crawl from 11:30pm till 3:30am

Hello all, I’ve been having this problem for a long time about the same time almost every night. Internet connection slows down to 2-3 mbps download but uploads are normal in the 40mbps. This happens almost every night for hours not no 5 minute thing.

I do not have a Xfinity gateway but my own all in one modem/router and thought it might be dying since I’ve had it for years so I bought some pricy xfinity compatible modem and separate WiFi 6 router but nothing has changed.

i have done everything like turn on and off everything, checked and made sure there are no reboot timers on. I checked the xfinity app for any interruptions in service but it says all is good. I log into the router and says Internet has connection. 

Everything is on and powered just feels like xfinity is limiting me for them hours almost every night.

 No problems during the day, the internet speeds are as they should be so I don’t know what gives.