Netgear EX7500 loses connection to router every night

I set up the EX7500 extender (AC2200) and it works perfectly during the day. I'm using it with a Netgear R7000P (AC2300) router. I have confirmed both the router and the extender have the current firmware. 

 

Something is happening overnight because the next morning the extender has stopped working. Instead of all 4 or 5 lights being solid blue, the only lights lit solid blue on the extender are the power light and the WPS light. It somehow loses its connection to the router every night, even though it was working perfectly the day before.  The only way to get it working again is to do a factory reset and start from scratch. Very time consuming. 

 

Given that the firmware is correct and current, what could be happening to the extender overnight?