Netgear WGR614v6 router No Internet Access problem?

I have a Netgear WGR614v6 router that I've been using it for 3 years. Suddenly there are intermittent No internet access problem (wired and wireless). At first, I just reboot the router and it will work. After a week, I can no longer connect to the internet even i reboot the router. Is there any way to fix it? How? Is there a problem if my router is turned on always? because i seldom put it off. Hope you can help me. Thanks...