So I would say that in the setup I have tried with different routers, every other device works just fine with the AC router and in the AC band. The SP3 is the only device that is very flaky with the AC band and should NOT be flaky. I should not have to be changing my router settings (which are the defaults anyway) in order to accommodate the SP3 faulty WiFi driver.
The latest updates made it better but they still need more work to make it work like any other laptop, tablet, or phone. My HP laptop connects to the AC band just fine and never drops, same for other Android tablets, etc.
I agree you should not have to fiddle with settings. I'm only comparing what works for ME with what others are posting. I tested briefly with a WRT1900 but with my preferred settings, not defaults I don't see the issues others are seeing as mine were fixed July 16.
do you have a 5.8GHz cordless p[hone there?