Xiaomi MiWifi mini wireless signal question

Installing and Using OpenWrt
15 
config wifi-device 'radio0'
	option type 'mac80211'
	option channel '40'
	option hwmode '11ac'
	option path 'pci0000:00/0000:00:00.0/0000:01:00.0'
	option htmode 'VHT80'
	option noscan '0'

config wifi-iface 'default_radio0'
	option device 'radio0'
	option network 'lan'
	option mode 'ap'
	option encryption 'psk2+ccmp'
	option key 'password_here'
	option macfilter 'allow'
	list maclist '00:00:00:00:00:00'
	option ssid 'WIFI 5G NAME HERE'

config wifi-device 'radio1'
	option type 'mac80211'
	option channel '3'
	option hwmode '11g'
	option path 'platform/10180000.wmac'
	option htmode 'HT40'
	option noscan '0'

config wifi-iface 'default_radio1'
	option device 'radio1'
	option network 'lan'
	option mode 'ap'
	option encryption 'psk2+ccmp'
	option key 'password_here'
	option macfilter 'allow'
	list maclist '00:00:00:00:00:00'
	option ssid 'WIFI 2G NAME HERE'

LEDE Reboot SNAPSHOT r3472

Not fully stable but usable with the settings above. If I add country code or transmit power value it becomes unstable.

And getting this error from time to time.

Mon Feb 20 04:07:27 2017 kern.err kernel: [53303.575047] ieee80211 phy1: rt2x00queue_write_tx_frame: Error - Dropping frame due to full tx queue 2 Mon Feb 20 04:07:27 2017 kern.err kernel: [53303.584492] ieee80211 phy1: rt2x00queue_write_tx_frame: Error - Dropping frame due to full tx queue 2 Mon Feb 20 04:07:27 2017 kern.err kernel: [53303.593953] ieee80211 phy1: rt2x00queue_write_tx_frame: Error - Dropping frame due to full tx queue 2 Mon Feb 20 04:07:27 2017 kern.err kernel: [53303.603401] ieee80211 phy1: rt2x00queue_write_tx_frame: Error - Dropping frame due to full tx queue 2 Mon Feb 20 04:07:27 2017 kern.err kernel: [53303.612847] ieee80211 phy1: rt2x00queue_write_tx_frame: Error - Dropping frame due to full tx queue 2 Mon Feb 20 04:07:27 2017 kern.err kernel: [53303.622297] ieee80211 phy1: rt2x00queue_write_tx_frame: Error - Dropping frame due to full tx queue 2 Mon Feb 20 04:07:27 2017 kern.err kernel: [53303.631748] ieee80211 phy1: rt2x00queue_write_tx_frame: Error - Dropping frame due to full tx queue 2 Mon Feb 20 04:07:27 2017 kern.err kernel: [53303.641192] ieee80211 phy1: rt2x00queue_write_tx_frame: Error - Dropping frame due to full tx queue 2

Speedtest wifi 2g: 6/7m with 2 walls distance 20-25 mbits DL 10-15 mbits UL.
5g seems to be getting capped to 50-60 mbits even if I'm standing next to the router.

Edit1:

All speedtest done with usb drive mounted.

Wired - http://beta.speedtest.net/result/6081768120
2G about 25 ft w/ 2/3 walls - http://www.speedtest.net/my-result/a/2654001492
2G about 30 ft w/ 3/4 walls - http://www.speedtest.net/my-result/a/2654014944
5G about 2 ft next to the router - http://www.speedtest.net/my-result/a/2654037149

Model: Xiaomi MiWiFi Mini
Firmware Version: LEDE Reboot SNAPSHOT r3472