# ViaVi Guides

> Practical, tested how-to guides from ViaVi (viavi.dk), written by Jimmi Frederiksen. Each guide states the exact device, firmware version and date it was tested on.

## Guides

- [How to make a UniFi Dream Router (UDR) fan quiet](https://guide.viavi.dk/unifi-dream-router-quiet-fan/): The UDR's fan is controlled by Ubiquiti's uhwd service, whose built-in table keeps the fan near 30% (about 2,000 RPM) at a normal 58 °C CPU temperature. Writing a calmer table to /etc/ustd/fan.conf and running `systemctl restart usdbd` drops it to about 630 RPM while still ramping to 39/70/100% at 70/80/90 °C CPU. Custom fancontrol scripts fight uhwd and make the fan pulse. Undo: `rm /etc/ustd/fan.conf && systemctl restart usdbd`. Tested 2026-10-24 on one UDR, UniFi OS 5.1.33; not tested on UDR7, UDM or other models.

## Files

- [quiet-fan.sh](https://guide.viavi.dk/unifi-dream-router-quiet-fan/quiet-fan.sh): POSIX shell script with install, status and undo. Refuses to run unless `ubnt-device-info model_short` returns UDR.