RT-AC5300 drops connection, is it the router or the client?

I've had the RT-AC5300 for around 3 weeks now and it's been working well, except with my laptop which has the Intel AC-7260 wireless network card. The connection constantly disconnects, whether I am using Smart Connect enabled or disabled and on both of the individual 5GHz bands. When I first received it I immediately updated to the firmware which was current at the time. I was going to return it, but then I decided to try the Merlin 380.57 firmware and it's been working like a champ,...

RT-AC5300 drops connection, is it the router or the client?