I work with a LTE modem. Normally when I plug it, ttyUSB0/ttyUSB1/ttyUSB2/ttyUSB3 appear. Suddenly it stops working and I don't know what happened. Why does it happen?
Thank you in advance
Update: more information about the modem
The modem even doesn't appear as usb detected (lsusb)
lsusb
Bus 001 Device 003: ID 0424:ec00 Standard Microsystems Corp. SMSC9512/9514 Fast Ethernet Adapter
Bus 001 Device 002: ID 0424:9514 Standard Microsystems Corp. SMC9514 Hub
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Information dmesg:
dmesg | grep usb
[ 0.070655] usbcore: registered new interface driver usbfs
[ 0.070710] usbcore: registered new interface driver hub
[ 0.070802] usbcore: registered new device driver usb
[ 0.339993] usbcore: registered new interface driver lan78xx
[ 0.340051] usbcore: registered new interface driver smsc95xx
[ 0.367935] dwc_otg 3f980000.usb: base=(ptrval)
[ 0.769196] dwc_otg 3f980000.usb: DWC OTG Controller
[ 0.769229] dwc_otg 3f980000.usb: new USB bus registered, assigned bus number 1
[ 0.769265] dwc_otg 3f980000.usb: irq 56, io mem 0x00000000
[ 0.769581] usb usb1: New USB device found, idVendor=1d6b, idProduct=0002, bcdDevice= 4.19
[ 0.769593] usb usb1: New USB device strings: Mfr=3, Product=2, SerialNumber=1
[ 0.769602] usb usb1: Product: DWC OTG Controller
[ 0.769612] usb usb1: Manufacturer: Linux 4.19.56-v7+ dwc_otg_hcd
[ 0.769621] usb usb1: SerialNumber: 3f980000.usb
[ 0.771222] usbcore: registered new interface driver usb-storage
[ 0.775835] usbcore: registered new interface driver usbhid
[ 0.775841] usbhid: USB HID core driver
[ 1.191896] usb 1-1: new high-speed USB device number 2 using dwc_otg
[ 1.432191] usb 1-1: New USB device found, idVendor=0424, idProduct=9514, bcdDevice= 2.00
[ 1.432206] usb 1-1: New USB device strings: Mfr=0, Product=0, SerialNumber=0
[ 1.751888] usb 1-1.1: new high-speed USB device number 3 using dwc_otg
[ 1.882172] usb 1-1.1: New USB device found, idVendor=0424, idProduct=ec00, bcdDevice= 2.00
[ 1.882186] usb 1-1.1: New USB device strings: Mfr=0, Product=0, SerialNumber=0
[ 1.975380] smsc95xx 1-1.1:1.0 eth0: register 'smsc95xx' at usb-3f980000.usb-1.1, smsc95xx USB 2.0 Ethernet,
b8:27:eb:8a:ea:fc
[ 5.112990] usbcore: registered new interface driver brcmfmac
dmesg
log in your question. – Dmitry Grigoryev Jun 27 '19 at 11:57