Wifi router turned red but ISP says I am connected

Oct 28, 2018
I have an optic fiber broadband connection which i use through wifi router. My router light is turned red and I cannot access the internet. I contacted my ISP but he says at his end I am showing logged in and connected to internet. Over the phone he told me to reboot the router and the same thing happened, I couldn't access internet yet he says it shows connected at his end. Although a techician will soon be visiting my place, I want to know what could possibly be the problem.
Thank You.