Internet has recently degraded significantly during peak hours to where it is no longer acceptable

Internet has recently degraded significantly during peak hours to where it is no longer acceptable.  We have not changed anything.  No additional devices.  No changes in home at all.  Internet signal is bow weaker and far parts of the house plus, during peak hours, all devices having terrible drop outs.  Considering dropping service and switching to other provider.  Devices are not new but also not horrifically old but the one that I use I notice the problem most on and it is an excellent quality iPhone 12 mini that I have no problems with for any other use.  I am thinking that the Xfinity gateway is starting to die.  I have pro experience with local area network administration and it feels like the gateway is struggling.  Can you advise?