Hill, I have tried to do the setting according to the blog and my router version and firmware was 2.0 SG.
I'm not sure it will have a different settings compared with that author's setting but I already contact with dlink customer service and their confirmed my unit is compatible with unifi.

So, what's probably was wrong??
I tried double and triple check my password it shouldn't be any minor mistake or whatever...

Anyone happen to have a same case with me, and probably have a solution to this problem, before have to use a final
resort that to turn in to dlink service centre?

Thanks, really appreciate it..
Drowning from offline, life's suck without logged into net...