How do you know when a modem is faulty?

A modem may be faulty if you experience persistent connectivity issues, such as intermittent disconnections or inability to connect to the internet despite a stable power supply. Additionally, if the modem's indicator lights are not functioning as expected—such as a solid red light instead of green—or if you can't access the modem's settings through a web browser, these are also signs of potential failure. Finally, if you've tried resetting the modem and the problems persist, it may need to be replaced.