Cute throughput on RB450G?

NAS === MT X86 5.26 === WIFI ~~~ NOTEBOOK (Download from NAS got 45mbps stable)
NAS === MT X86 5.26 === WIRED TO NOTEBOOK (Download from NAS got 986mbps stable)
NAS === RB450G 5.26 === WIFI ~~~ NOTEBOOK (Download from NAS got 30mbps stable)
NAS === RB450G 5.26 === WIRED TO NOTEBOOK (Download from NAS got 198mbps stable)

All exactly the same hardware and same settings, just changed from PC X86 to RB450G.

PC X86 Settings:
NAS go to Ether1 (IF Queue: Multi Queue Ethernet Default)
LAN go to Ether2 (IF Queue: Multi Queue Ethernet Default)
Mode Masquerade

RB450G Settings:
Switch All Ports = oFF
NAS go to Ether1 (IF Queue: Only Hardware Queue)
LAN go to Ether2 (IF Queue: Only Hardware Queue)
Mode Masquerade

WIFI tested:
TP-Link TL-WR702N (Mode AP, 20MHz, Channel 6, Indoor, CPU AR9331)
TP-Link TL-WA701ND (Mode AP, 20MHz, Channel 6, Indoor, CPU AR9331)
TP-Link TL-WA730RE (Mode AP, 20MHz, Channel 6, Indoor, CPU AR9331)
UBNT Bullet M2-Ti (Mode AP, 20MHz, Channel 6, Indoor, CPU AR7240)
All WiFi got the same result!

The question is: IF wired can go almost 200mbps, then why wireless capped at 30mbps? IF PC can give me 45mbps on WIFI, then RB450G must be able to give me the same 45mbps.

Update:
NAS === MT X86 5.26 === WIRED TO 100mbps NIC (Download from NAS got 98.6mbps stable)
NAS === RB450G 5.26 === WIRED TO 100mbps NIC (Download from NAS got 71.2mbps stable)
MTU all set to 1500