CONFIG_LTE_LOCK_BANDS causes error in nrf v1.3.0

[Yusuke]

when I add a line below to mqtt_simple program, it causes error. How to fix this?

CONFIG_LTE_LOCK_BANDS=y

*** Booting Zephyr OS build v2.3.0-rc1-ncs1  ***
The MQTT simple sample started
LTE Link Connecting ...
LTE Link Connected!
ERROR: getaddrinfo failed -11
ERROR: mqtt_connect -47

It seems that at_cmd_write in lte_lc.c gives an error -5

<lte_lc.c>

#if defined(CONFIG_LTE_LOCK_BANDS)
	/* Set LTE band lock (volatile setting).
	 * Has to be done every time before activating the modem.
	 */
	if (at_cmd_write(lock_bands, NULL, 0, NULL) != 0) {
		return -EIO;
	}
#endif

[Martin Lesund]

Hi Yusuke,
You also need to set the configuration for which bands you want to lock:

CONFIG_LTE_LOCK_BAND_MASK="10000001000000001100"

[Yusuke]

I added these two lines but it gives the same result. no luck..

CONFIG_LTE_LOCK_BANDS=y
CONFIG_LTE_LOCK_BAND_MASK="10000001000000001100"

This is the whole prj.conf

#
# Copyright (c) 2019 Nordic Semiconductor ASA
#
# SPDX-License-Identifier: LicenseRef-BSD-5-Clause-Nordic
#

# Networking
CONFIG_NETWORKING=y
CONFIG_NET_NATIVE=n
CONFIG_NET_SOCKETS_OFFLOAD=y
CONFIG_NET_SOCKETS=y
CONFIG_NET_SOCKETS_POSIX_NAMES=y

# LTE link control
CONFIG_LTE_LINK_CONTROL=y
CONFIG_LTE_AUTO_INIT_AND_CONNECT=n

# BSD library
CONFIG_BSD_LIBRARY=y

# AT Host
CONFIG_UART_INTERRUPT_DRIVEN=y
CONFIG_AT_HOST_LIBRARY=y

# MQTT
CONFIG_MQTT_LIB=y
CONFIG_MQTT_LIB_TLS=n

# Appliaction
#CONFIG_MQTT_PUB_TOPIC="/my/publish/topic"
#CONFIG_MQTT_SUB_TOPIC="/my/subscribe/topic"
#CONFIG_MQTT_CLIENT_ID="my-client-id"
#CONFIG_MQTT_BROKER_HOSTNAME="mqtt.eclipse.org"
#CONFIG_MQTT_BROKER_PORT=1883

# Main thread
CONFIG_MAIN_STACK_SIZE=4096

CONFIG_HEAP_MEM_POOL_SIZE=2048

CONFIG_LTE_LOCK_BANDS=y
CONFIG_LTE_LOCK_BAND_MASK="10000001000000001100"

[Yusuke]

Can you try mqtt_simple adding the two lines in the same environment?