Huawei Modem in LEDE using NCM, copy file to /lib/netifd/proto and make it executable (chmod +x huawei_dhcp.sh), kmod-usb-net-huawei-cdc-ncm and usb-modeswitch need to be installed

huawei_dhcp.sh

#!/bin/sh

. /lib/functions.sh
. ../netifd-proto.sh
init_proto "$@"

proto_huawei_dhcp_init_config() {
	available=1
	proto_config_add_string "device:device"
	proto_config_add_string pin
	proto_config_add_string apn
	proto_config_add_string user
	proto_config_add_string password
	proto_config_add_boolean defaultroute
	proto_config_add_boolean peerdns
	proto_config_add_int metric
}

proto_huawei_dhcp_setup() {
	local config="$1"
	local iface="$2"

	local device pin apn user password defaultroute peerdns metric
	json_get_vars device pin apn user password defaultroute peerdns metric

	[ -n "$device" ] || {
		echo "No control device specified"
		proto_notify_error "$config" NO_DEVICE
		proto_set_available "$config" 0
		return 1
	}
	[ -e "$device" ] || {
		echo "Control device not valid"
		proto_set_available "$config" 0
		return 1
	}
	[ -n "$apn" ] || {
		echo "No APN specified"
		proto_notify_error "$config" NO_APN
		return 1
	}

	echo -e "ATZ\r" >$device
	sleep 5
	[ -n "$pin" ] && {
		echo -e "AT+CPIN=\"$pin\"\r" >$device
		sleep 5
	}
	echo -e "AT^NDISDUP=1,1,\"$apn\",\"$user\",\"$password\"\r" >$device
	sleep 5

	echo "Connected, starting DHCP on $iface"

	proto_init_update "$iface" 1
	proto_send_update "$config"

	json_init
	json_add_string name "${config}_4"
	json_add_string ifname "@$config"
	json_add_string proto "dhcp"
	[ -n "$defaultroute" ] && json_add_boolean defaultroute "$defaultroute"
	[ -n "$peerdns" ] && json_add_boolean peerdns "$peerdns"
	[ -n "$metric" ] && json_add_int metric "$metric"
	ubus call network add_dynamic "$(json_dump)"
}

proto_huawei_dhcp_teardown() {
	local config="$1"

	local device
	json_get_vars device

	[ -n "$device" ] || {
		echo "No control device specified"
		proto_notify_error "$config" NO_DEVICE
		proto_set_available "$config" 0
		return 1
	}
	[ -e "$device" ] || {
		echo "Control device not valid"
		proto_set_available "$config" 0
		return 1
	}

	echo "Stopping network"

	echo -e "AT^NDISDUP=1,0\r" >$device

	proto_init_update "*" 0
	proto_send_update "$config"
}

add_protocol huawei_dhcp

sample_config

config interface 'wwan'
  option proto 'huawei_dhcp'
  option ifname 'wwan0'
  option device '/dev/cdc-wdm0'
  option pin '1234'
  option apn 'internet'