I'm going to try merlin , i just what make sure below step is correct or not?
1.Into CFE Mode flash RT-AC68U_378.56_beta2-X5.7-20151017

2.Back to CFE Mode click "Restore default NVRAM values" -> reboot

3.Update RT-AC68U_380.70_0-X7.9 in merlin firmware upgrade

4.in merlin webshell input commands to make USB work

nvram set model=RT-AC68U
nvram set HW_ver=170
nvram commit

5.setup router username, password ,wifi ... done

ur fan is to blow cold air in? or suck hot air out?

if cannot press reset button anymore after flashed to merlin, then how to perform step 2?

1.Into CFE Mode flash RT-AC68U_378.56_beta2-X5.7-20151017
2.Back to CFE Mode click "Restore default NVRAM values" -> reboot

gonna press reset button while power on the router to enter into CFE mode, right?
besides, i was having problem to get into CFE mode.. the page wont show up most of the time.
i did try to set a manual IP address, it will somehow brought me into the main page, but when i chose the file and clicked upload, it won't respond and then connection time out.
which step went wrong here? (i was on LAN connection)

Still, have no luck update the FW via CFE page after another 1-2 hours non-stop trying last night.

Fortunately, found another method, got to update the Tenda FW to version "AC18_kf_V15.03.3.7(4031)AC18", once updated, it will allow u to update to 3rd party FW directly from the Tenda page .(No need to go through CFE page anymore)
After upgrade done, another issue encountered. It cannot get the WAN IP although I already set to PPPoE and inserted my Unifi credential, no Internet access. Got to manually put in the WAN IP, subnet, etc... after applied, it somehow set it back to auto obtain the WAN IP and managed to access to Internet at last. I started to suspect that my unit might be lemon unit... 

Just a question, why can't we straight update FW to 380.70_0-X7.9? Instead have to update 378.56_beta2-X5.7-20151017 first?

wow u also have cooler

holy shit I love the temperature.

usb powered?

any other adapter voltage can be used?

sadly my 75 degree, imma need to find some cooling soon.
[attachmentid=10077090]
[attachmentid=10077089]

the hotter the shorter life span?

Have you tried overclock Cpu?

Using
nvram set clkfreq=1000,800
nvram commit

I don't have my ac18 yet, but I did using these commands on my Huawei WS880 to overclock till 900,667.

I also have another question here, WiFi 5g is better on Koolshare or Tenda firmware? Or insignificant based on your experience?

Thx

Thinking for NAS application. USB SHARING.

Thanks.. one more question..any setting I need to do to get fullspeed..my unifi is 800mb but I only can get 600++ from speedtest.net..if I test from tm web it more worst..only 300-400mbs

i think my cable lor..need to try cat6

he tried dy what.
http://speedtest.tm.com.my

No. It is USB sharing from ext hdd.

Sometimes server overloaded right? Imagine you alone already consume 800mbps, if there're 20 people doing the speedtest to the server at the same time, sure you will be getting fluctuated results. Especially right now ppl are very excited to perform speedtest.