Extremely slow internet connection

Our internet speeds (download AND upload) have been constantly dropping below 1MB/s. This is a recent issue and has not happened over the past year of having this service. We have restarted our internet through the app and by unplugging + replugging the modem/router - speeds recover for a couple minutes then drop below 1MB/s again. Xfinity assistant and the app are all telling us that the connection is good and nothing is wrong, but it is clearly not good. We have not been able to connect to a human assistant. Can someone help?