Merlin Setup

What Merlin adds over stock ASUS firmware, how to install it, and how to update or roll back safely.

Published September 11, 2024 · Updated May 8, 2026

Merlin Setup

Router: ASUS RT-AX88U

Merlin is a community-maintained fork of ASUS stock firmware. It deliberately stays close to the stock codebase and feature set while adding the automation hooks and extension points that make router-side homelab work manageable.12

Merlin vs Stock ASUS

Merlin keeps the familiar ASUSWRT UI and most stock features. The practical difference is that it adds a small set of router-admin extension points that stock firmware does not expose cleanly:12

  • Event-driven user scripts stored in /jffs/scripts
  • Scheduled tasks through Merlin's cron integration
  • Custom service configs and postconf hooks under /jffs/configs
  • Entware support through Merlin's documented setup path
  • VPN Director instead of ASUS's VPN Fusion flow on supported models

That is the real reason to run Merlin on a homelab router: not to replace ASUSWRT with a different platform, but to make the existing platform scriptable.12

Installation

Before You Start

  • Download the latest stable firmware image for your exact router model from the Merlin download page. RT-AX88U remains on Merlin's supported-model list.13
  • Back up the current config in Administration -> System Settings -> Backup
  • If you already use Merlin scripts or custom configs, also back up /jffs before you flash.45

Flash

  1. Open Administration -> Firmware Upgrade -> Choose File.
  2. Select the Merlin firmware image for your model.
  3. Upload it and wait for the router to reboot. Merlin is flashed the same way as an original ASUS firmware update, and existing settings are generally preserved.2

Post-installation

Enable JFFS custom scripts/configs in Administration -> System first, then reboot once. After that, create the directories Merlin expects for scripts and config overrides.45

ssh admin@192.168.1.1
 
# Create Merlin working directories
mkdir -p /jffs/scripts /jffs/configs
chmod 755 /jffs/scripts

Updating Later

Scripts in /jffs/scripts, config overrides in /jffs/configs, and Entware packages usually survive firmware updates. The update process is the same as the initial flash, but keep backups before any branch change or cleanup-heavy upgrade.245

Roll Back To Stock Firmware

  1. Download the matching official ASUS firmware for your exact router model.
  2. Open Administration -> Firmware Upgrade -> Choose File.
  3. Upload the stock firmware file and wait for reboot.

Anything stored in /jffs should be backed up before rollback.45

Footnotes

  1. Asuswrt-Merlin is designed to retain the stock ASUSWRT feature set and performance while adding targeted fixes and administrator-focused enhancements rather than radical platform changes: Asuswrt-Merlin About. ↩ ↩2 ↩3 ↩4

  2. Merlin's official features list describes the firmware as easy to install like a stock firmware update and highlights the added admin features that matter for homelab use, including user scripts, scheduled tasks, custom config files, Entware, and VPN Director: Asuswrt-Merlin Features. ↩ ↩2 ↩3 ↩4 ↩5

  3. RT-AX88U remains on Merlin's supported model list in the official project documentation: Asuswrt-Merlin About. ↩

  4. Merlin user scripts live under /jffs/scripts, require JFFS support to be enabled in Administration -> System, and should be executable shell scripts with a shebang: Asuswrt-Merlin User Scripts. ↩ ↩2 ↩3 ↩4

  5. Merlin custom config overrides live under /jffs/configs; *.add files append to firmware-generated configs while postconf scripts let you rewrite generated files before the service starts: Asuswrt-Merlin Custom Config Files. ↩ ↩2 ↩3 ↩4

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