The router won't boot up.
Verify that the power supply unit is fully plugged into the router and a working electrical outlet. Also, verify that the power supply unit is not defective. You can do this by testing the power supply on another router or similar device that uses the same power supply unit. If it is damaged, obtain a new power supply that outputs a minimum of 12V 0.5A.
If the power supply if working, then the power connector on the router is defective. If you are comfortable with soldering, follow this guide to replace the barrel power connector. If you do not want to perform any soldering, follow this guide instead to replace the entire motherboard.
Connected devices have a weak or no wireless signal.
The specified maximum distance for Wireless-G routers is 100 meters or 328 feet. The wireless signal grows weaker as your devices moves further away from it. The signal will also be weaker if it has to travel through walls. Reduce the distance and number of walls between the router and the devices to improve the signal.
If the antennas on the rear are damaged, you need to replace them. The model number for the antennas is HGA7T. Follow these instructions to replace them.
If the antenna ports on the router itself are defective, you need to either replace the antenna ports themselves or the entire motherboard unit. If you are comfortable with soldering, follow this guide to replace them. If you do not want to perform any soldering, follow these instructions to replace the entire motherboard.
The devices are connected to the router, but there is no internet connectivity.
Verify that there is a functional CAT5 or better ethernet cable connected to the internet port on the rear. Obtain a new ethernet cable if it is damaged.
Verify that there is a valid internet connection in the building where the router is being used. Contact your internet service provider if there is a problem with the building's internet connection.