What is Netgear Router Error Code 651? Netgear Router error code 651 usually occurs due to a faulty network connection. This complication usually happens when1- The modem or other connecting services report an error. 2- Wrong registry files affect the function of the router. 3- Miniature drive port files ‘Raspppoe. Sys’ are mediators that connect the hardware to the device. If those files are saved in the wrong place, such error will appear. 4- If you are using the wrong IP address for the site, then this problem will come up.