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.
nslookup stackexchange.com 188.8.131.52fails
ping stackexchange.comtimes out
Interestingly if I connect to the Router's wifi guest, it works fine.