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BIOS and Hardware

This page covers the NUC's BIOS configuration, power settings, UPS, and thermal management.

BIOS Access

To access the NUC BIOS:

  1. Connect a monitor and keyboard to the NUC.
  2. Power on (or reboot) the NUC.
  3. Press F2 repeatedly during the boot splash screen.

Physical access required

BIOS settings cannot be changed remotely via SSH. You must be physically present with a monitor and keyboard connected to the NUC.

Power On After AC Loss

This is the most critical BIOS setting for unattended operation. It ensures the NUC automatically boots when power is restored after an outage.

Path: Power > Secondary Power Settings > After Power Failure > Power On

Setting Description
Stay Off NUC remains off after power loss (default on most NUCs)
Last State NUC returns to whatever state it was in before power loss
Power On NUC always boots when power is restored

The setting must be set to Power On for the gateway to recover automatically from power outages.

UPS

The NUC should be connected to a UPS (Uninterruptible Power Supply) to handle brief power interruptions without a full reboot cycle.

Recommended: APC Back-UPS 600VA (BX600C-IN) or similar.

A UPS protects against:

  • Momentary power flickers that would otherwise cause a hard reboot.
  • Short outages (5--15 minutes depending on load and UPS capacity).
  • Voltage sags and surges that can damage hardware over time.

The UPS does not need to be connected via USB for monitoring -- its primary purpose here is to provide a power buffer.

Temperature Monitoring

Temperature is monitored via Netdata.

Dashboard path: Hardware > Sensors > Temperature

Normal Ranges

State Temperature Status
Idle 40 -- 55 C Normal
Under load 60 -- 80 C Normal
Warning 85 C Investigate cooling
Critical / Shutdown 100 C+ Thermal protection triggers

Thermal shutdown

At 100 C and above, the NUC will perform an emergency thermal shutdown to prevent hardware damage. This causes an ungraceful Asterisk termination and drops all active calls.

Temperature Alerts

Configure Netdata alerts to notify when CPU temperature exceeds 85 C. This gives time to investigate before a thermal shutdown occurs.

Ventilation

  • Keep the NUC mounted in a rack with active fan ventilation.
  • Do not block the NUC's intake or exhaust vents.
  • Clean dust from vents and fans every few months.
  • Ensure adequate airflow around the NUC -- do not stack equipment directly on top of it.

Never compile software on the NUC

Compiling from source causes sustained 100% CPU load across all cores, which can push the NUC to thermal shutdown. This happened during a Netdata source build. Always use pre-built Debian packages or binaries. If no package is available, compile on another machine and transfer the binary.

Hardware Failure Recovery

If the NUC fails and needs to be replaced:

  1. Obtain a replacement Intel NUC (or equivalent small-form-factor PC).
  2. Install Debian.
  3. Configure the NNI interface (enp86s0) with the Tata IP and routes.
  4. Install WireGuard and restore the wg0.conf (same private key to avoid re-keying the cloud peer).
  5. Install Asterisk 22 from packages and restore pjsip.conf and extensions.conf.
  6. Install and configure cloudflared with the tunnel credentials.
  7. Set BIOS to "Power On after AC loss."
  8. Connect to UPS and mount in rack.

Keep backups of /etc/wireguard/wg0.conf, /etc/asterisk/, and /etc/cloudflared/ off-site.