The EM7455 supports only raw-ip. For this to work with the upstream kernel driver (qmi_wwan) and qmicli, you’ll need kernel >= 4.4 and then make sure the kernel knows it has to work in raw-ip mode, e.g. using qmicli:
qmicli -d /dev/cdc-wdm0 --set-expected-data-format=raw-ip (this will set some sysfs property to tell the kernel to switch the associated network interface to raw-ip)
Once both the kernel and the device are aligned on the data format, and once you have connected the device normally with qmicli/qmi-network, you will need to either manually configure the IP and routing settings using the values given in
qmicli -d /dev/cdc-wdm0 --wds-get-current-settings; or otherwise try DHCP using a DHCP client that supports raw-ip interfaces (the one in busybox? never remember…).
For some context, ModemManager/NetworkManager uses the WDS Get Current Settings message to setup the manual IP and routing settings in normal Linux distributions for this device.