Technical Tip: How to avoid the Random LTE Modem Disconnectinos on FortiGate-40F-3G-4G

[tonylin1]

Description	This article describes how to avoid random LTE Modem Disconnections on FortiGate-40F-3G-4G.
Scope	FortiGate-40F-3G-4G v7.0.8, v7.2.4 and above.
Solution	When the LTE Modem is not stable, the behavior is shown as follows: diagnose debug crashlog read 475: 2025-07-17 17:01:28 Interface wwan is brought up. process_id=219, process_name="lted" 476: 2025-07-17 17:17:42 Interface wwan is brought up. process_id=219, process_name="lted" 477: 2025-07-17 17:34:24 Interface wwan is brought up. process_id=219, process_name="lted" 478: 2025-07-17 17:50:58 Interface wwan is brought up. process_id=219, process_name="lted" diagnose debug application lted -1 diagnose debug enable 2025-07-17 16:17:11 qmi_dev_read_msg(341)-219: Can not read QMI device 0 : timeout 2025-07-17 16:17:11 usb_qmi_wwan_wds_get_packet_service_status(2956)-219: Failed read msg(No such device) 2025-07-17 16:17:11 sierra_qmi_wwan_check_modem_data_connection(918)-219: wds_get_packet_service_status failed! Tried 1 times! 2025-07-17 16:17:17 qmi_dev_read_msg(381)-219: This message is an indication message, ignore it and read again. 2025-07-17 16:17:27 qmi_dev_read_msg(341)-219: Can not read QMI device 0 : timeout 2025-07-17 16:17:27 usb_qmi_wwan_wds_get_packet_service_status(2956)-219: Failed read msg(No such device) 2025-07-17 16:17:27 sierra_qmi_wwan_check_modem_data_connection(918)-219: wds_get_packet_service_status failed! Tried 2 times! 2025-07-17 16:17:37 qmi_dev_read_msg(341)-219: Can not read QMI device 0 : timeout 2025-07-17 16:17:37 usb_qmi_wwan_wds_get_packet_service_status(2956)-219: Failed read msg(No such device) 2025-07-17 16:17:37 sierra_qmi_wwan_check_modem_data_connection(918)-219: wds_get_packet_service_status failed! Tried 3 times! 2025-07-17 16:17:37 update_modem_status(544)-219: Modem activated success but connection check fails! 544 To stop the debug, use the commands given below: diagnose debug application lted 0 diagnose debug disable diagnose debug reset Solution.