I update 9.8.2.1 via *.tar* and no changes.
The version number (9.2.8.2) has changed a bit, but it's okay. 
The Amlogic project branch of CE 9.2.7 "non-ng" build contains exactly the same driver, so it's a little weird.
I need more information, so you should follow exactly the following steps:
- Start the box without connecting the USB stick.
- dmesg -c
This prints the dmesg and also deletes it. From now on, only recent changes are relevant. - cat /etc/os-release | grep PRETTY_NAME
- lsmod | grep cfg80211
- Now connect the USB wifi adapter.
- dmesg -c
- lsmod | grep cfg80211
I connected the TL-WN722N v1 to my M8Q as an example, but I would expect something similar:
M8Q:~ # dmesg -c
...
M8Q:~ # cat /etc/os-release | grep PRETTY_NAME
PRETTY_NAME="LibreELEC (dtech): 9.2.8.2"
M8Q:~ # lsmod | grep cfg80211
cfg80211 206547 1 8188eu
The USB device is now connected...
M8Q:~ # dmesg -c
[ 886.150548@3] usb 1-1.2: new high-speed USB device number 4 using dwc_otg
[ 886.273154@3] usb 1-1.2: New USB device found, idVendor=0cf3, idProduct=9271
[ 886.273247@3] usb 1-1.2: New USB device strings: Mfr=16, Product=32, SerialNumber=48
[ 886.273295@3] usb 1-1.2: Product: USB2.0 WLAN
[ 886.273362@3] usb 1-1.2: Manufacturer: ATHEROS
[ 886.273406@3] usb 1-1.2: SerialNumber: 12345
[ 886.391053@1] usb 1-1.2: ath9k_htc: Firmware htc_9271.fw requested
[ 886.393564@1] usbcore: registered new interface driver ath9k_htc
[ 886.704285@1] usb 1-1.2: ath9k_htc: Transferred FW: htc_9271.fw, size: 50980
[ 886.942404@1] ath9k_htc 1-1.2:1.0: ath9k_htc: HTC initialized with 33 credits
[ 887.184809@1] ath9k_htc 1-1.2:1.0: ath9k_htc: FW Version: 1.3
[ 887.184822@1] ath: EEPROM regdomain: 0x0
[ 887.184828@1] ath: EEPROM indicates default country code should be used
[ 887.184832@1] ath: doing EEPROM country->regdmn map search
[ 887.184839@1] ath: country maps to regdmn code: 0x3a
[ 887.184845@1] ath: Country alpha2 being used: US
[ 887.184850@1] ath: Regpair used: 0x3a
[ 887.189399@1] ieee80211 phy1: Atheros AR9271 Rev:1
[ 887.189473@1] cfg80211: Calling CRDA for country: US
[ 887.189850@1] cfg80211: Regulatory domain changed to country: US
[ 887.189864@1] cfg80211: (start_freq - end_freq @ bandwidth), (max_antenna_gain, max_eirp)
[ 887.189872@1] cfg80211: (2402000 KHz - 2472000 KHz @ 40000 KHz), (3000 mBi, 0 mBm)
[ 887.189878@1] cfg80211: (5170000 KHz - 5250000 KHz @ 80000 KHz), (2300 mBi, 0 mBm)
[ 887.189885@1] cfg80211: (5250000 KHz - 5330000 KHz @ 80000 KHz), (2300 mBi, 0 mBm)
[ 887.189892@1] cfg80211: (5490000 KHz - 5730000 KHz @ 160000 KHz), (2300 mBi, 0 mBm)
[ 887.189898@1] cfg80211: (5735000 KHz - 5835000 KHz @ 80000 KHz), (3000 mBi, 0 mBm)
[ 887.189905@1] cfg80211: (57240000 KHz - 71000000 KHz @ 2160000 KHz), (4000 mBi, 0 mBm)
[ 887.312071@3] IPv6: ADDRCONF(NETDEV_UP): wlan1: link is not ready
M8Q:~ # lsmod | grep cfg80211
cfg80211 206547 4 ath,mac80211,ath9k_htc,8188e
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If this is possible, you should do this under my image on your MXIII-clone as well as from the other box under CE with same USB wifi stick.
By the way, I also ordered a WN821N today, the version will unfortunately only be revealed if it is in my hands.