Wifi keeps dropping connection to TV's, cell phone and laptop

my signal drops multiple times every day. I have tried resetting the modem unplugging devices multiple times. At least half the time I turn one of the TVs on it is no longer connected to the Internet. I work from home and regularly get disconnected on conference calls right now I am using the upgraded Xfinity combo modem, but I've also tried connecting my Aris, surfboard and Eero router I use with no problem at our other house and I'm still having the same issue. The previous owner of this house said they had the same issue as well but Comcast didn't want to do anything because the issue was intermittent and couldn't be duplicated on demand