A router's firmware is the operating system that runs it. The one installed by the manufacturer is designed to be simple and often stops receiving updates after a few years. OpenWrt is a free, Linux-based operating system that can be installed on a great many routers and access points in place of the original firmware. It is not always the right choice, but in some situations it turns an ordinary device into a far more capable tool.
What you gain
The practical benefits fall into four groups:
- security updates that continue even after the manufacturer has abandoned the model;
- advanced features: VLANs, multiple separate Wi-Fi networks, SQM against bufferbloat, WireGuard VPN, custom DNS, detailed firewall rules;
- transparency: the code is public, with no hidden telemetry to the manufacturer;
- extra packages: you install only the features you need, from an encrypted DNS client to traffic statistics.
The web interface is called LuCI and is more technical than commercial ones, but well organised. If you prefer, you can manage everything from the command line over SSH, with plain-text configuration files that are easy to save and compare.
What you lose
Not everything is a gain. Some proprietary features disappear: the manufacturer's smartphone app, built-in parental controls, sometimes the hardware acceleration that lets cheap routers route a gigabit without straining the CPU. On some models the free Wi-Fi drivers perform worse than the original ones; on others they perform better. Above all, you lose manufacturer support: if something goes wrong, you rely on the documentation and the community forum.
Is your router supported?
The project maintains a list of supported devices, the so-called Table of Hardware, with a page for each model. First of all you need to identify the exact model and the hardware revision, printed on the label under the router: two versions with the same commercial name can have completely different chips, and only one may be supported.
Other useful criteria:
| Aspect | What to check |
|---|---|
| Flash memory and RAM | Models with little memory are discouraged and fall behind on releases |
| Wi-Fi chip | Some chip makers have mature free drivers, others do not |
| Installation method | From the original web interface, via TFTP or through a serial port |
| Support status | Stable release available or only development images |
If you are buying a router specifically for OpenWrt, start from the list of recommended devices, not from the shop.
How installation works, broadly
The model's page tells you which image to download. There are usually two files: a factory image, to install OpenWrt starting from the original firmware, and a sysupgrade image, to update an existing OpenWrt installation. Using the wrong one is one of the most common mistakes.
- Read the whole model page, including the notes on hardware revisions.
- Connect the computer to the router with a cable, never over Wi-Fi.
- Upload the factory image from the original firmware's update page, if the model allows it.
- Wait without cutting the power until the router has fully rebooted.
- Connect to the default address, set an admin password immediately and configure Wi-Fi, which is off by default.
A power cut during flashing can leave the router unusable or require recovery via TFTP or serial. That is why it is wise to do your first installation on a device you can live without for a few days.
Updates and packages
OpenWrt publishes stable releases and maintenance updates. An upgrade between releases replaces the whole system: the configuration is normally kept, but packages installed by hand have to be reinstalled. There are tools that build a custom image already including your chosen packages, which makes maintenance much easier.
Before every update, download the configuration backup from the system page. It is a small archive that can be restored in a few seconds.
When it is worth it
OpenWrt makes sense if the factory router no longer gets updates, if you need features such as VLANs or SQM that the model does not offer, or if you want to reuse an old device as an access point or as a router for a separate network. It does not make sense if your current router does its job well, receives updates and whoever manages it has neither the time nor the wish to learn. In my work I recommend it mainly to people who are already somewhat familiar with networking and want full control over their own.
In short
- OpenWrt extends a router's life and adds VLANs, SQM, VPN and fine-grained control.
- You may lose the manufacturer's app, hardware acceleration and support.
- Check the model and hardware revision in the official list before buying or installing.
- Use the factory image for the first installation and sysupgrade for updates.
- Always save the configuration before upgrading.
