I have an ASUS RT-AC66U router (802.11ac - 2.4GHz and 5GHz) and an ASUS USB-AC56 802.11ac Wireless USB Adapter.
The router firmware is updated, all the QoS nonsense is disabled, and I'm using DHCP with manual MAC-IP assignments for devices on the network.
The main symptom: I get 75-80Mbit/s down over the net, and 145-180Mbit/s down from my ReadyNAS. But upload is weirdly capping out at ~2.91Mbit/s to both/either. I.e. I can upload to the NAS at 2.90816Mbit/s (355KibiByte/s exactly in Windows), or the internet, or with both combined they each average half that.
Signal strength is good and seems rock-solid. Windows 8.1 reports a 390Mbit/s connection and full strength.
I'm at a complete loss as to what to try next to diagnose this problem. Occasionally - very occasionally, and just for a few seconds, I've seen uploads at 20-30Mbps, again maxed out weirdly and in an unresponsive way. But then it's back to ~2.91Mbps.
The thing is, Googling 355KibiByte/sec gives loads of results from similar people - saying various uploads to OneDrive and other seemingly unrelated situations (http://forums.dlink.com/index.php?topic=55196.0, http://answers.microsoft.com/en-us/onedrive/forum/sdperformance-sdimpperf/onedrive-file-downloads-appear-to-be-throttled-at/064407a4-6cd8-4e69-86f8-71b862922e1f).
Any tips of next steps I can try would be very welcome. I'm a developer by trade so not afraid of in-depth tools or processes... What is the significance of 355KibiBytes/sec? What can I do?
Edit: I've used inSSIDer to check there's nothing else nearby, channel-wise. I'm using 80MHz channel bandwidth. I installed gcc, manually built iperf on the NAS box directly.
NAS-to-PC:
[ 4] 0.00-1.01 sec 15.7 MiBytes 131 Mbits/sec
PC-to-NAS:
[ 4] 0.00-10.01 sec 2.87 MiBytes 2.41 Mbits/sec
New edit: just tried iperf (in fact iperf3) to check with my MacBook Pro - more than 220 Mbps both ways. I've had different USB dongles on the PC - it's got to be a Windows issue. Any ideas still very welcome :'(
