I have a very similar problem to him, I just purchased the A7000 Adapter yesterday, along with it we purchased the Linksys EA9500 AC5400 yada yada, my old router was broken and I had a linksys g-band adapter before, maxed out at like 14 mbps, the new router got us to 140 mbps, and with the new A7000 on 5 GHz I got about 130 mbps.  All is good, except I keep having ping spikes of 1000+ ms, every like 10-20-30 seconds.  I would say maybe it is something new, but I pinged with 5 GHz and that is the worst, and I pinged at 2.4 GHz and that wasn't much better, and then I tried my old adapter and pinged maxed out at 24 ms, average about 8 ms.  I originally thought it was only while I was gaming, but that isn't the case either, so I am not sure what to do.  I also tried the disabling feature he mentioned and that didn't affect it.  I also tried the Windows 10 Network Reset, didn't do anything as well.  I also tried a non-3.0 usb slot, nothing as well.

Ps, I didn't have these spikes with the old router and adapter combo, and my brother doesn't appear to be lagging even further away in the house with a lower quality adapter.