HTC M8 WI-FI issues, what can I do?

[AC Question]

HTC M8 WI-FI issues

My HTC M8 has stopped to connect to the router (DIR 635) for 2 days. Moreover, it disconnects the internet from the router. Without htc connected, the WiFi is working (PC+tablet). But HTC gone mad. What should I do? Factory reset? I thought it was the router to blame, but it seems that HTC is the one with issue. The error shows that the once HTC connected, "the network is changed". HTC has been updated to Marshmallow 6.0 since February.

 

[B. Diddy]

Welcome to Android Central! First, try rebooting the router by unplugging its power for 10 seconds, then plugging back in again.

If the problem persists, try wiping the phone's cache partition: https://support.t-mobile.com/docs/DOC-10672