Roku will no longer connect to the router's Wi-Fi.

 I have been running my Roku premier streaming stick from a network extender that is connected wirelessly to a cox panoramic router. Everything had been working great up until yesterday. All of a sudden my Roku will no longer connect to the routers wifi. But it still connects to my mobile hotspot fine. None of the routers settings have been changed recently. I ran system updates on Roku, reset network settings, power cycled both router and Roku, and everything else that has been suggested online. I've even tried factory resetting both Roku and extender and set back up from scratch. What would cause it to suddenly not connect when it has been connected just fine for like 3 months, and nothing has changed,? How can I fix this very frustrating issue??