D-Link DIR-850L (Ver.A1)
After the DIR-820L-A1 test unit, thanks to D-Link Malaysia again for this gigabit device which has custom FW to work with UniFi 
Product Photo
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Basically the design outlook, radio chip (RealTek base) and size is exactly the same like the DIR-820L-A1, only difference this device is gigabit ports, nice 
Product information & reference:
- https://wikidevi.com/wiki/D-Link_DIR-850L_rev_A1
- http://www.dlink.com.my/products/?idproduct=611&idCategory=285
- UniFi firmware download --> https://sg.mydlink.com/support#
Like the DIR-820L-A1, UniFi firmware need to download from D-Link Singapore website
At the time of this article, the current latest UniFi FW version is "v1.09SG" (hmmm, why named "SG" 
)
Setup for UniFi
My setup for UniFi as follows :
Basically the overall FW design it's the same like the DIR-820L-A1 (Ver 1.01~1.03), but surprisingly this Ver 1.09 has enhanced the QoS function to include both Downl/Up links control, nice
But the QoS rules still the same basic function with limited entries & ports, hmmm....
IPv6 Connection
Work out of the box without any issue
WiFi Testing - on Laptops
Tested both 2.4 & 5.8 spectrum on some of my laptops result as follows:
For 2.4GHz, I'm quite surprise with the good performance 
Considered the fact it's a RealTek radio chip, somemore without external antenna, nice job here 
For 5.8GHz, the result it's almost like 2.4GHz, actually I was expecting more, so the result is considered ok la
WiFi Testing - on Mobile Devices
Mobile devices can get sensitive with WiFi connection. Since I hardly play with the RealTek WiFi, so I tested both 2.4GHz & 5.8 spectrum on some of my mobile devices like: Zopo ZP980+, Nexus4, Samsung S4, ASUS Zenfone5, ASUS FonePad7 ... even on my very old Xperia Arc 
Android versions ranging from JB 4.1/4.2 to the current latest KK 4.4, both stock and custom build (CyanogenMod)
Mobile Devices (2.4GHz)
Overall result on 2.4GHz seem good, most of my mobile devices can get similar result
Mobile Devices (5.8GHz)
Overall result on 5GHz seem ok only, not as good as 2.4GHz, down/up load rate seem varied ...
Except for the QoS (need more function on the rules set) & DDNS (only support DynDNS), overall I'm happy with this little toys.
Hope to see more FW improvement work & other router choices from D-Link