AC68U Firmware Version:3.0.0.4.380_3831 bug?

[follower]

Former issue
http://www.snbforums.com/threads/weird-experience-ac68u-with-firmware-3-0-0-4-380-3831.34809/

http://www.snbforums.com/threads/whats-wrong-with-this-system-log.34839/

Result: same thing happens

Windows event

The IP address lease 'My IP' for the Network Card with network address
'xxx' has been denied by the DHCP server '192.168.1.1'
(The DHCP Server sent a DHCPNACK message).

The system detected an address conflict for IP address 'My IP'
with the system having network hardware address 'Router MAC address'.
Network operations on this system may be disrupted as a result.

There is no issue with direct connection to ISP.
I've tested so many things: Nvram clear, reboot, factory default, manual setting after Nvram clear, change NIC, reinstall windows and many things.


FIX
Stop using MAC Clone: no more DHCP issue
Still have this issue: all of wireless devices are slowed or disconnected from Wi-Fi connection when I test the speed for my wired computer at speedtest.net. There is no issue with file downloading..

Possibilities
Firmware Version:3.0.0.4.380_3831 has following bugs.
1. MAC Clone issue.
2. MAC clone with DMZ issue.
3. DHCP issue.
4. QoS issue.(QoS disabled)
5. This router is going to die?