Like many others, I have spent an inordinate amount of time trying to resolve both AC 7260 and AC 7265 issues - mainly throughput falling off a cliff after a very short period of time. In my case, I was able to determine the issue and resolve it after a fashion.
I use a Bluetooth mouse extensively with my laptop. I noticed that, when I had Intel Wireless Bluetooth enabled in Device Manager, and was connected to a 802.11N router on the 2.4GHz band, throughput would drop off to a snail's pace. If I set the HT mode to Disabled (which corresponds to 802.11G), then wi-fi connectivity was fine, albeit limited to 54Mbps. On the other hand, if I enabled HT or VHT and disabled Bluetooth, then 802.11N connectivity was absolutely fine. Finally, connecting on the 5GHz band with Bluetooth enabled also worked fine.
My conclusion is that the AC 7260/7265 have a Bluetooth/Wi-fi co-existence issue. While the potential for interference between the two standards is well known, but the Bluetooth specification has specific mechanisms for mitigating it. The extent to which this is affecting the AC7260/7265 is way above and beyond anything I have encountered before - there is absolutely no way the issue should be this severe. Whether this is a fundamental flaw in the Intel hardware or an unresolved driver issue I don't know, but what I do know is that it's definitely unacceptable.
I finally found the perfect router for my AC-7260 card. It is ASUS RT-AC56U. I have pinged the router for days without any lost packet. It is also quite fast:
Well, I still agree that Intel should fine-tune the drivers for other access points also. It is so pain in the *** to travel anywhere else since, unlike at home, I can't choose the router in hotels and conference places.
I have multiple APs at my house, though I mainly use the ATT2WIRE (arguably the most used AP/Router in the US) and this ghetto card will NOT stay connected for more than 30 minutes. I have though (very briefly) seen solid 802.11B speeds out of it. Oh yeah, and a big shout out to Intel for promising repeatedly over the last three months to "contact" me about the problem. Anyone want to take bets on whether or not I've yet to receive even a SINGLE call??
So I've loaded the latest drivers (17.1.14) and I must say they are quite an improvement. Normal internet surfing doesn't drop anymore on 2.4 ghz (2 days of testing on tplink wn1043), but it does drop when streaming to my TV. In 1,5 hours it dropped three times, but luckily it fixed itself every time. Of course the movie was interrupted each time. So I am starting to believe, that they can actually make this work. Just a little more. Can't comment on the 5GHZ range because I don't have a suitable router.