Internet slows down at the same time everyday and returns to normal after 12 hours

So on christmas eve my internet speeds suddenly slowed down around 6pm Eastern, I chatted with an agent after being on hold for almost an hour and she took me through the whole "turn it off and on again" power cycling  and whatnot. Nothing she suggested worked, at the same time I also noticed that there were two power outages on the outage map, one was fairly close to my area. I asked if there was a possibility these outages could affect my service, but she said she didn't see any outages. The following morning the internet was back to normal so I cancelled an appt that was set up, but like the previous day, around 6pm my speeds were slowed. Between christmas eve and new years eve, I talked with various different agents, each taking me through the same thing and each time I brought up the whole nearby outages, it seemed like they just weren't listening. Even had two technicians come out on two seperate occasions, and they did everything they could inside of my house  and outside (Check coax cables, run a new line from the pole to my house, give me a new modem/router...) and yet again at 6pm my speeds are slow again. Can barely load the Xfinity page, and each time this has happened those same outages have been on the outage map and the site always says they can't find a signal to my router/issues detected....can anyone please give me some answers!