wifi stop workinf frequently

Hi there.

Basically I'm so happy with my C6300 router and it literally works fine accept an issue that wifi stops at some events are particular.

I have approximately 7-8 devices are hooked on the router with wifi and currently added a chromecast which uses 5G. but the most of time it connected to wifi, the whole wifi is no longer works. and the only thing I noticed is that the last 2 lights on the bottom side turned to stuck from normal blinking. Actually I have had this same issue with this in very occansion but now it got worse unforunately. The only way to get wifi back is to reboot the router for right now.

I'm 100% not sure of this issue is from chromecast but something went wrong. so I'm in need of getting technical assistance to make it work properly from you. I would appreciate if got some troubleshoots ot directions I may try on.

Thanks