After issuing some AT commands to RM520N-GL, I lost the AT port at /dev/ttyUSB2 and also /dev/ttyUSB3, and I can no longer send it any AT commands.
I have only /dev/ttyUSB0 and /dev/ttyUSB1. The ethernet port of the board also gives 192.168.225.1.
Is there a way to reset RM520N-GL, so I could regain the AT port?
FYI, cat /sys/kernel/debug/usb/devices returns
T: Bus=01 Lev=01 Prnt=01 Port=00 Cnt=01 Dev#= 3 Spd=480 MxCh= 0
D: Ver= 2.10 Cls=00(>ifc ) Sub=00 Prot=00 MxPS=64 #Cfgs= 1
P: Vendor=2c7c ProdID=0801 Rev= 5.04
S: Manufacturer=Quectel
S: Product=RM520N-GL
S: SerialNumber=hidden
C:* #Ifs= 6 Cfg#= 1 Atr=a0 MxPwr=500mA
A: FirstIf#= 0 IfCount= 2 Cls=ef(misc ) Sub=04 Prot=01
I:* If#= 0 Alt= 0 #EPs= 1 Cls=ef(misc ) Sub=04 Prot=01 Driver=rndis_host
E: Ad=81(I) Atr=03(Int.) MxPS= 8 Ivl=32ms
I:* If#= 1 Alt= 0 #EPs= 2 Cls=0a(data ) Sub=00 Prot=00 Driver=rndis_host
E: Ad=8e(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms
E: Ad=0f(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms
I:* If#= 2 Alt= 0 #EPs= 2 Cls=ff(vend.) Sub=ff Prot=30 Driver=option
E: Ad=01(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms
E: Ad=82(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms
I:* If#= 3 Alt= 0 #EPs= 3 Cls=ff(vend.) Sub=00 Prot=40 Driver=option
E: Ad=84(I) Atr=03(Int.) MxPS= 10 Ivl=32ms
E: Ad=83(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms
E: Ad=02(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms
I:* If#= 4 Alt= 0 #EPs= 3 Cls=ff(vend.) Sub=00 Prot=00 Driver=qmi_wwan
E: Ad=86(I) Atr=03(Int.) MxPS= 10 Ivl=32ms
E: Ad=85(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms
E: Ad=03(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms
I:* If#= 5 Alt= 0 #EPs= 3 Cls=ff(vend.) Sub=00 Prot=00 Driver=qmi_wwan
E: Ad=88(I) Atr=03(Int.) MxPS= 10 Ivl=32ms
E: Ad=87(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms
E: Ad=04(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms