I think there’s driver problem.
The built-in wifi could never switch to the faster 802.11n mode, and it can not be forced.
It’s always stuck at the 802.11g mode (54 mbps)
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I tried plugging in this old USB Wifi adapter : http://www.tp-link.co.id/download/TL-WN723N_V3.html#Driver
And it straight up goes to 802.11n ! 150 mbps, very nice.
iwconfig wlxa0f3c1158a01
wlxa0f3c1158a01 IEEE 802.11bgn ESSID:“Graha34” Nickname:"<WIFI@REALTEK>"
Mode:Managed Frequency:2.442 GHz Access Point: F4:EC:38:E9:A1:A8
Bit Rate:150 Mb/s Sensitivity:0/0
Retry:off RTS thr:off Fragment thr:off
Encryption key:------- Security mode:open
Power Management:off
Link Quality=81/100 Signal level=-46 dBm Noise level=0 dBm
Rx invalid nwid:0 Rx invalid crypt:0 Rx invalid frag:0
Tx excessive retries:0 Invalid misc:0 Missed beacon:0
So in the meanwhile, looks like I’ll be using this little USB wifi adapter. It’s just much faster.