To insure that you have good internet, bypass the router and connect a PC direct to the modem with an Ethernet cable, power cycle both and test. Also run speed tests to ensure you are getting what you paid for from the ISP. Once all is okay, then attach the router in between the modem and router. Power cycle all and test. Be sure to use good Ethernet cables as they are known to cause issues and note just because they are new does not mean they are good. Also be sure you used the correct power adapters for each device.