C6300-100NAS AC1750 modem router combo - Most sites not accessible, but some can be reached

Hi All,

I have a C6300-100NAS AC1750 modem router combo. It had been working fine till now, but for the past couple of days, I am experiencing some weird connectivity issues. I have a solid internet light on the modem and my ISP has verified that there seem to be no issues from their side and my modem is online. For most of the sites that I try to reach, I get an error saying something like " Server cannot be found". But I can access other sites like google, apple etc. I have tried connecting using a lan cable as well. Both the 2.4 ghz as well as 5 GHz as well as the LAN lights all stay stable for a while, but start blinking after a while.

I have tried power cycling the network already and it hasn't worked. Any pointers on what steps I can take to resolve this issue?

Thanks and Regards,

AD