ALPON X4 troubleshooting

Diagnostic reference for the ALPON X4 industrial edge IoT computer. Each issue lists the observable symptom, the probable cause, and the minimal fix. Work through the categories in order: power, then LEDs and boot, then connectivity, then GPIO and USB, then the operating system, then ALPON Cloud.

Power and boot

The ALPON X4 accepts three independent power inputs: USB-C PD, DC terminal block (9 to 30 V), and PoE+ on the PoE variant SKU. Under-voltage triggers Restricted Mode, which disables USB ports, the GPIO Add-on 5 V rail, HDMI, and the RGB LED while keeping the Raspberry Pi CM4, LTE modem, and both Ethernet ports alive for remote diagnostics.

LED states and what they mean

The ALPON X4 surfaces device health on four front-panel LEDs: Power, Connection, Cellular, and a programmable RGB. Reading these indicators is the fastest first diagnostic when shell access is not yet available.

What does each LED pattern indicate?

Connectivity (LTE, Wi-Fi, Ethernet)

The ALPON X4 has four network paths: LTE Cat 4, dual-band Wi-Fi, 1 Gbps Ethernet (ETH/G), and 100 Mbps Ethernet (ETH). When more than one path is available, the Sixfab Connect agent handles failover in priority order. Most connectivity problems reduce to antenna torque, eSIM profile state, or link priority.

GPIO Add-on and USB

The GPIO Add-on port is an RJ45 connector exposing six configurable Raspberry Pi CM4 GPIO pins (SPI5, UART4, UART0, I2C2, I2C3) at 3.3 V logic, plus a 5 V / 1 A power output gated by GPIO 21. The two USB 2.0 ports share a 1 A combined current budget.

# Enable the GPIO Add-on 5 V rail and check for fault
import RPi.GPIO as GPIO

GPIO.setmode(GPIO.BCM)
GPIO.setup(21, GPIO.OUT)   # ADDON_PWS_EN
GPIO.setup(20, GPIO.IN)    # ADDON_PWS_FAULT

GPIO.output(21, GPIO.HIGH) # Enable the rail

if GPIO.input(20) == GPIO.LOW:
    print("Fault: overcurrent, overtemperature, or reverse voltage")
else:
    print("Add-on rail enabled, 5 V available on Pin 8")

ALPON X4 OS and SSH

The ALPON X4 ships with ALPON X4 OS, a Sixfab-customized 64-bit Raspberry Pi OS Lite (Bookworm) image with the Sixfab Connect agent, ModemManager, Docker, OpenSSH, mDNS, and the hardware watchdog daemon pre-installed. The default user is alpon with password sixfab; the hostname follows the format alpon-<MAC>.

# Two reliable ways to reach the device
ssh alpon@alpon-<MAC>.local      # mDNS, requires same VLAN
ssh alpon@<DEVICE_IP>           # Direct, works across routed subnets

# Default password: sixfab, change before production
sudo passwd alpon

# Verify connectivity first
ping -c 3 1.1.1.1

# Confirm the system clock is current
timedatectl
sudo timedatectl set-ntp true

# Repair any half-configured packages
sudo dpkg --configure -a
sudo apt install -f

# Refresh and retry; reboot if a kernel package was upgraded
sudo apt update
sudo apt upgrade -y

ALPON Cloud and provisioning

ALPON Cloud (connect.sixfab.com) handles device registration, fleet health monitoring, browser-based remote terminal access, container deployment, OTA updates, eSIM profile management, and network failover. The on-device agent (sixfab-connect) is pre-installed in the ALPON X4 OS image.

Before you contact support

Running through these checks covers more than 90% of field issues and gives Sixfab support the context needed for a fast resolution. Run them top to bottom; each step takes under a minute.

Collecting a support bundle

If you can run a shell on the device (SSH or HDMI), this single block captures the journal, kernel ring buffer, throttle state, modem status, and OS release into one archive. Attach it to your ticket if you can; otherwise the items in the checklist above are enough to start.

# Single-shot bundle, run on the device over SSH
sudo journalctl -b -n 2000 > ~/alpon-x4-journal.log
dmesg > ~/alpon-x4-dmesg.log
vcgencmd get_throttled > ~/alpon-x4-power.log
mmcli -m 0 > ~/alpon-x4-modem.log
cat /etc/os-release > ~/alpon-x4-os.log
tar czf ~/alpon-x4-support.tar.gz ~/alpon-x4-*.log
# Copy the archive to your computer with scp, WinSCP, or Cyberduck.