What Hardware version is your router? Look at sticker under router.
What Firmware version is currently loaded? Found on routers web page under status.
What region are you located?
Are you wired or wireless connected to the router?
What ISP Service do you have? Cable or DSL?
What ISP Modem do you have? Stand Alone or built in router?
What ISP Modem make and model do you have?
If this modem has a built in router, it's best to bridge the modem. Having 2 routers on the same line can cause connection problems.
To tell if the modem is bridged or not, look at the routers web page, Status/Device Info/Wan Section, if there is a 192.168.0.# address in the WAN IP address field, then the modem is not bridged.
Check cable between Modem and Router, swap out to be sure. Cat6 is recommended.
I'm having same issue. I thought it might be the ISP, but when I disconnect from router, and connect directly to modem, I have no issues. I've been troubleshooting, resetting to factory, etc... No good. I did get wireless service for 1 day, but then it starting dropping and got progressively worse with every passing day. Now, nothing. I've given up. I've had it for 3 years now. It might just be that time to get something new. One more thing I haven't tried (firmware update). I'll give up after that. I've got a CISCO router ready to take it's place.