I have Fios. Multiple times per day, I find myself having to reboot the router due to dropped connections to the internet. It is true whether I am using wireless capability or direct with LAN drop (hard wire). Success for a few hours, and then it does it again. I will search blogs, but wondering if there is a consistent fix.
Could be faulty cable if its happening on the lan side as well. How long have you had the router? Could be router going bad also. Try plugging into another lan port and also change the cable if you can. Let me know if that works.
