Worsening internet connections.

My internet service has been getting progressively worse over the last several months. There have been several work crews on my area, even though Comcast says there are no problems. I have used the Xfinity app which tells me my connection to the modem is very slow and restart the modem. I used to have to reboot the modem once a week. Now it's daily, and it doesn't help. It doesn't matter what system I use. I have Apple phones. I have Dell laptops. My main computer is connected via ethernet directly to the modem. All connections are dropped, including my Xfinity security system installed by Xfinity. A service tech came out a year ago and changed the main splitter. It didn't change a thing. My TV service is fine. There is nothing wrong with my internal wiring or my TV's would have issues too. How do I get someone to look into this and not just have an automated system repeatedly telling me to restart my modem?