I recently purchased the TP-Link AC1900 Smart WiFi router (Archer A9).  Set it up as an access point.  It's connected by a Cat 6 Ethernet cable to my primary gateway (modem/router). About once a day the WiFi stops working on the TP-Link AC1900/Archer A9 and the internet globe icon on the front of it turns orange instead of green (phones, tablets, and anything else connected to it by WiFi lose internet even though they're still showing as connected to the router).  At the same time, the primary gateway still functions properly and devices connected to the primary gateway still work fine and speed tests show that the primary gateway's WiFi is getting 700-800 Mbps download speed. Further, my Apple TV and and audio system, which are connected to the TP-Link AC1900/Archer A9 by Ethernet cable plugged into the back of it still work fine and fast. 

Obviously the internet signal is getting to the TP-Link AC1900/Archer A9's input port and obviously it's able to pass the signal along through its Ethernet output ports.  I am not super tech-savvy, but based on this troubleshooting, the problem does not appear to by my ISP, nor my primary gateway, nor the Ethernet cable between the primary gateway and the TP-Link AC1900/Archer A9.  Rather the problem seems to be the TP-Link AC1900/Archer A9's WiFi/router functionality.  If I unplug the power cord from it and plug it back in a minute later, it starts working correctly again - until the problem returns, which is usually the next day.  We have only had this for a couple weeks so I can return it I need to, but thought I would reach out on this forum to see if anyone has suggestions or experiences for changing a setting or anything else to get it working better.  Or does it sound like this particular unit just has a problem and i'd be better off getting a different router/access point?  Thanks for any insight.