ASUS RT-AC66U rev. B1 AsusWrt-Merlin Firmware 386.13.0

The AsusWrt-Merlin firmware was developed with the primary goal of boosting the original ASUS firmware, fix bugs and also add new improvements. This package includes a customized firmware targeted at ASUS routers that brings various changes without modifying the interface of the original firmware.

Changes:

- NOTE: all the models supported by Asuswrt-Merlin on the 386_xx series are now officialy on Asus' End of Life list, which means unless there are new major security issues, no new updates will be provided by Asus.
- Asuswrt-Merlin will tentatively attempt to continue to provide updates and fixes until the end of 2024, at which point all the 386_xx models will no longer be actively maintained.
- UPDATED: openvpn to 2.6.10.
- UPDATED: miniupnpd to 2.3.6.
- UPDATED: tor to 0.4.7.16.
- UPDATED: OUI database used by networkmap and the webui.
- CHANGED: QOS/Classification page can now resolve local IPv6 addresses.
- CHANGED: Display tracked connections on the QoS/Classification page even if QoS isn't set to Adaptive QoS.
- CHANGED: Prevent the use of Apple's iCloud Private Relay when enabling "Prevent client auto DoH".
- CHANGED: NAT Passthrough page - removed the "Enabled + NAT Helper" option as the firewall no longer blocks traffic when set to disabled. This is back to the former behaviour, where this setting only controls whether or not to load the NAT helper. You might need to readjust that setting if you had previously changed it.
- CHANGED: SIP, RTSP and H323 ALG (NAT helpers) are now disabled by default, as these legacy features tend to create issues with modern VoIP setups. This change will only apply to people doing a factory default reset of their router.
- FIXED: CVE-2023-48795 in dropbear.
- FIXED: Various issues with the QOS Classification page.
- FIXED: UPNP leases without a description would not appear on the Forwarded Ports page.
- FIXED: web server crashing when entering certain settings on the Network Filter Page. Bypassed bug in closed source validation code for now.
- FIXED: Concurrent cronjob changes through cru could cause collisions, leading to missing jobs (dave14305)

Installation

- Simply flash it like any regular update. You should not need to reset to factory defaults (see note below for exceptions). You can revert back to an original Asus firmware at any time just by flashing a firmware downloaded from Asus's website.
- If the firmware upgrade fails, try rebooting your router to free up sufficient memory, without any USB disk plugged in, then try flashing it again.
- If you run into any issue after an upgrade and you haven't done so,try doing a factory default reset as well.
- Always read the changelog, as mandatory resets will be mentionned there when they are necessary.
- In all of these cases, do NOT load a saved copy of your settings! This would be the same thing as NOT resetting at all, as you will simply re-enter any invalid setting you wanted to get rid of. Make sure to create a new backup of your settings after reconfiguring.

NOTE:

- Resetting to factory default after flashing is strongly recommended for the following cases: Updating from a firmware version that is more than 3 releases older or Switching from a Tomato/DD-WRT/OpenWRT firmware

Installation Notes:

- This custom firmware can be applied like any regular update.
- You should not need to reset to factory defaults.
- You can revert back to an original ASUS firmware at any time.
- Do not load a saved copy of your settings.  

About Router Firmware:

Before you consider downloading this firmware, go to the system information page of the router and make sure that the currently installed version isn't either newer or matching this release.

Due to the large variety of router models and different methods for upgrading the device, it is highly recommended that you read and, above all, understand the installation steps before you apply the new firmware, even if you are a power user.

In theory, these steps shouldn't be much of a hassle for anyone, because manufacturers try to make them as easy as possible, even if they don't always succeed. Basically, you must upload the new firmware to the router through its administration page and allow it to upgrade.

If you install a new version, you can expect increased security levels, different vulnerability issues to be resolved, improved overall performance and transfer speeds, enhanced compatibility with other devices, added support for newly developed technologies, as well as several other changes.

If you're looking for certain safety measures, remember that it would be best if you perform the upload using an Ethernet cable rather than a wireless connection, which can be interrupted easily. Also, make sure you don't power off the router or use its buttons during the installation, if you wish avoid any malfunctions.

If this firmware meets your current needs, get the desired version and apply it to your router unit; if not, check with our website as often as possible so that you don't miss the update that will improve your device.