UEFI can cause problems with Mobile Broadbands because MB´s is identifying wrong. The fix is to disable device indentify string /lib/udev/rules.d/40-usb_modeswitch.rules file. An example ZTE MF 688.

1. Diagnose the device
dmesg | grep GSM
dmesg | grep sr
dmesg | grep usbserial
lsusb

… the result for lsusb:

mint@mint-SATELLITE-C50-B ~ $ lsusb
Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
Bus 001 Device 004: ID 1a81:2203 Holtek Semiconductor, Inc. Laser Gaming mouse
Bus 001 Device 005: ID 0930:0227 Toshiba Corp.
Bus 001 Device 003: ID 1a40:0101 Terminus Technology Inc. 4-Port HUB
Bus 001 Device 002: ID 04f2:b446 Chicony Electronics Co., Ltd
Bus 001 Device 006: ID 19d2:2000 ZTE WCDMA Technologies MSM MF627/MF628/MF628+/MF636+ HSDPA/HSUPA
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub

2. Modbrobe the device

sudo modprobe usbserial vendor=0x19d2 product 0x2000

3. Re-diagnose /dev/sr
ls /dev/sr*

…. the result
/dev/sr0

4. Eject sr device
eject /dev/sr0

5. Connect via NetworkManager