RT-AC68U slow WiFi download speed, upload fine

[Asus_83]

We have recently purchased two Asus RT-AC68U routers to act as wireless APs in our office. We have a 100/100 Mbps internet connection and wired speeds test consistently in the 80-90 Mbps range in both directions using speedtest.net

Unfortunately, while on WiFi (5Ghz - iPhone 6/iPad Air) download speeds (tested using speedtest.net app) never exceed 30-40 Mbps while upload is fine and consistently in the 80-90 Mbps range. I'm at my wits end and can't figure our what the problem could be.

Currently, settings are at their factory defaults but I have tried adjusting various settings to no avail. Firmware is up to date, actually loaded Merlin's version to see if that would make a difference (no).

Can anyone point me in the right direction? Why would only downstream speeds be affected?


UPDATE:

More info, I looked in the Wireless log and this is what i'm seeing:

Mode : AP Only

Stations (flags: P=Powersave Mode, S=Short GI, T=STBC, A=Associated, U=Authenticated)
----------------------------------------
MAC IP Address RSSI Rx/Tx Rate Connected Flags

F0:99:BF:14:2C:6C -49dBm 24/433 Mbps 0:07:55 PS AU


This would explain the slow download speed, but why is the Rx rate so low ?

 

[RMerlin]

More info, I looked in the Wireless log and this is what i'm seeing:

Mode : AP Only

Stations (flags: P=Powersave Mode, S=Short GI, T=STBC, A=Associated, U=Authenticated)
----------------------------------------
MAC IP Address RSSI Rx/Tx Rate Connected Flags

F0:99:BF:14:2C:6C -49dBm 24/433 Mbps 0:07:55 PS AU


This would explain the slow download speed, but why is the Rx rate so low ?

Power management. The rate will increase as there is actual traffic.

 

[Asus_83]

Power management. The rate will increase as there is actual traffic.

You're right. While doing a speed test I refreshed the wireless log and the rate jumped to 433/433.

I found the root of the problem.....the firewall. For testing purposes I disabled IPS, URL filtering, and App control on our firewall and as soon as I did that download speeds returned to normal.

Still not sure why wired clients only take a small hit in performance vs. wireless clients but at least I now know that my issue is caused by another device and my wireless network works just fine