Link>
Welcome!What Hardware version is your router? Look at sticker under router.
Link>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?
Has a Factory Reset been performed?
What ISP Service do you have? Cable or DSL?
What ISP Modem Mfr. and model # do you have?
Any network switches installed?
Disconnect the router from the ISP modem and use only 1 wired LAN pc. Does the PC connect to the routers web page? Ping the routers IP address from a command line.
Check cable between Modem and Router and PCs, swap out to be sure. Link>
Cat6 is recommended.If you have experienced this issue on multiple routers, and they seem to keep malfunctioning, it would seem that the issue lies elsewhere, up stream on the WAN side on the router or down stream on the LAN site.
You might take this router to a different location, friend, family's or another place and check to see how it works there and see if the problem follows.
FYI:
Bridge Mode vs Relay vs Acess Point (AP) / Routers vs Dedicated Acess Points (AP)