ac815s at command error

Hello. I've bought AC815S from ebay, my phone carrier uses B3(main), B1, B7(sub).

AC815S supports CA(up to 3 bands thanks to software update), but it's auto-setting only uses B3 so I want to set CA for better speed.

After googling, I knew it can be done with at commands, but stuck like this;

at!entercnd="fallow"
at!entercnd="fallow"
ERROR

at!band=?
at!band=?
Index, Name
00, All Bands
01, LTE Only
02, 4G Only
03, 4G and LTE Only
04, 2G Only

OK
at!band=05,"3bandCA",0,45
at!band=05,"3bandCA",0,45
ERROR

(at command is NOT case-sensitive)

IDK whether at!band must be do after at!entercnd or not, but mr1100 seems to can be done without at!entercnd.

(external link:https://www.waveform.com/a/b/guides/mr1100-band-locking)

I attach some infos about my device-hope to help solving the problem.

!GSTATUS:
Current Time: 10672 Mode: ONLINE
System mode: LTE PS state: Attached
EMM state: Registered Normal Service
RRC state: RRC Connected
IMS reg state: No Srv

PCC:
LTE band: B3
LTE bw: 20 MHz
LTE Rx chan: 1550
LTE Tx chan: 19550
RSSI (dBm): -68.6
RSRP (dBm): -100.2
RSRQ (dB): -11.3
RSSNR (dB): 8
Tx Power (dBm):
LTE Cell ID: 2490892
Physical Cell ID: 149
TAC: 24

ATI
ATI
Manufacturer: Netgear, Incorporated
Model: AirCard 815S
Revision: NTG9X40C_11.14.08.28 r5400 ntgrbc-fwbuild4 2017/08/24 16:02:31
IMEI: (deleted)
IMEI SV: 6
FSN: (deleted)
+GCAP: +CGSM