- Check all connections between the router and the modem, and make sure that they are secure.
- Verify that your service plan supports the internet connection you are trying to achieve.
- Test the modem to make sure it is properly transmitting a signal.
- Disable and then re-enable any firewalls between the router and the modem.
- Run a virus scan on both the router and the modem.
- If the problem persists, reset the router to its default settings.