If the Online LED on the router is off, it indicates that there is an internet connection issue. To troubleshoot this Arris router online light not on problem, proceed with the easy instructions given on this web page.
Check if the power cable is firmly connected between the Arris router and the power source. Note: If possible, do not use an outlet controlled by a wall switch for the connection.
Check if you are using the correct Ethernet cable for establishing a connection between the Arris router and your computer.
Check if the Wi-Fi LED stays lit. If you have turned off Broadcast SSID, you need to enter the network name manually.