ASUS RT-AC66U-A1 [FW 3.0.0.1.372]
Setup UniFi
Pretty much the same setup like all other ASUSWRT devices ..
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WiFi Setup
General setup for both 2.4 & 5 GHz, I prefer to assign specific channel number, no Auto-mode.
I always turn-off WPS & set "Short" preamble for both 2.4 & 5 GHz
QoS - Basic Setup
Turn-on QoS function, enter both Up/Down load speed according to your subscribed package
(mine just upgraded to 10Mbps recently )
I just setup some basic rules as follows (you may need to setup/tweak according to your specific requirements)
WiFi Test
This is the most important test for me as I really want to know how this AC beast will perform ....
On my Acer-TM8371 (Intel AGN5100 WiFi Adapter) @ 5GHz
Excellent speed !
I guess this is the best my Acer can go already, but I still believe this beast can do better ...
So I pulled out my Dell Latitude E5400 (same Intel AGN5100 WiFi Adapter) to test on the 5GHz again, and the result is ..
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Excellent speed too, especially the Read speed seem to be better than my Acer TM8371
(Note: On the speed shown, during connection transfer it will show 300Mbps, after no transfer it will show 150Mbps)
Up to now, this is the fastest 5GHz result I've ever get on my 2 old laptops
I believe newer laptop with better 5GHz & hardware spec might do better than this
WiFi Test @ 2.4GHz
Good speed too !
(Click the above link to read more ...)
WiFi Test With PCE-AC66 --> The Ultimate 802.11ac Speed 
(Click the above link to read more ...)
USB - Download Manager (BT)
I formatted an external HDD with Ext3, insert into the device, can identify without any issue
My main purpose is torrenting, so just go to the following and install the Download Manager 
Follow the steps to complete DM installation ...
Take note this process may take some time, be patient to wait for the installation to complete ....
Once installation completed, click it to start DM
ASUSWRT's DM is based on Transmission, features & functions pretty the same like previous ASUSWRT FW
Let's torrenting gao-gao, full speed ahead on my VIP10
Overall tested & stressed (especially on wireless testings) for 3 days with some 15 different type of devices connected to it ..
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This beast still kicking alive, no hang no slow-down, both UniFi internet & IPTV no disconnection/connection issue
Only thing it can get very hot easily, especially under stress-test 
So better get cooling fan or something to cool it down if you intend to torture it gao-gao
Really enjoy this toys, unforgettable AC speed experience, robust & stable, another impressive Knight indeed !