My MacBook (El Capitan 10.11.2) one day cannot connect to the internet via wifi. It work solidly beforehand.
My router setting has not changed. Nor have any device white/black-listing. Other devices can connect to the router and internet fine.
ping 192.168.1.1worksnslookup stackexchange.comworksnslookup stackexchange.com 8.8.8.8failsping stackexchange.comtimes out
Interestingly if I connect to the Router's wifi guest, it works fine.