After upgrading kernel-default to 5.3.18-lp152.72.1 my mobile broadband card is
no longer recognized by the NetworkManager. It works again when booting with
any previous version of kernel-default.

# lsusb -d 0bdb:1926
Bus 002 Device 002: ID 0bdb:1926 Ericsson Business Mobile Networks BV H5321 gw
Mobile Broadband Module

Relevant journal entries:

kernel: cdc_wdm 2-4:1.5: cdc-wdm0: USB WDM device
kernel: cdc_wdm 2-4:1.8: cdc-wdm1: USB WDM device
kernel: usbcore: registered new interface driver cdc_wdm
kernel: cdc_acm 2-4:1.1: ttyACM0: USB ACM device
kernel: cdc_acm 2-4:1.3: ttyACM1: USB ACM device
kernel: cdc_ncm 2-4:1.6: MAC-Address: XX:XX:XX:XX:XX:XX
kernel: cdc_ncm 2-4:1.6 wwan0: register 'cdc_ncm' at usb-0000:00:14.0-4, Mobile
Broadband Network Device, XX:XX:XX:XX:XX:XX
kernel: usbcore: registered new interface driver cdc_ncm
kernel: cdc_acm 2-4:1.9: ttyACM2: USB ACM device
kernel: usbcore: registered new interface driver cdc_acm
kernel: cdc_acm: USB Abstract Control Model driver for USB modems and ISDN
adapters
kernel: usbcore: registered new interface driver cdc_mbim
systemd-udevd[510]: Using default interface naming scheme 'v245'.
systemd-udevd[510]: ethtool: autonegotiation is unset or enabled, the speed and
duplex are not writable.
kernel: cdc_ncm 2-4:1.6 wwp0s20u4i6: renamed from wwan0
...
kernel: cdc_acm 2-4:1.3: acm_port_activate - usb_submit_urb(ctrl irq) failed
kernel: cdc_acm 2-4:1.1: acm_port_activate - usb_submit_urb(ctrl irq) failed
...
ModemManager[1508]: <info>  [device
/sys/devices/pci0000:00/0000:00:14.0/usb2/2-4] creating modem with plugin
'Ericsson MBM' and '6' ports
ModemManager[1508]: <warn>  Could not grab port (usbmisc/cdc-wdm1): 'Cannot add
port 'usbmisc/cdc-wdm1', unsupported'
ModemManager[1508]: <warn>  Could not grab port (usbmisc/cdc-wdm0): 'Cannot add
port 'usbmisc/cdc-wdm0', unsupported'
dbus-daemon[1960]: [session uid=1000 pid=1960] Activating service
name='org.kde.ActivityManager' requested by ':1.23' (uid=1000 pid=2138
comm="/usr/lib64/libexec/org_kde_powerdevil ")
ModemManager[1508]: <warn>  Could not grab port (tty/ttyACM1): 'Cannot add port
'tty/ttyACM1', unhandled serial type'
ModemManager[1508]: <warn>  Could not grab port (tty/ttyACM0): 'Cannot add port
'tty/ttyACM0', unhandled serial type'
ModemManager[1508]: <warn>  Couldn't create modem for device
'/sys/devices/pci0000:00/0000:00:14.0/usb2/2-4': Failed to find primary AT port