Boosting performance of Asus RT-N66U

Over time my home network has grown and years are changed also the habits of consuming media at home. When I bought Asus RT-N66U some years ago it was well performing home router. Now came the point when continuing the old way was not an option anymore as things were degraded a lot. Performance boost was needed and here is what I did to get my veteran router back on track.

Asus RT-N66U home router.

As a number of connected devices has grown at home and also multimedia consumption going up I finally had to do something to boost the performance of my Asus RT-N66U. It’s a good box that is able to carry out also some not-so-home-user-scenarios and it can perform well but with out-of-box firmware it is like a good guy with bad suit.


Original firmware and DD-WRT I tried had both their own problems I was not able to solve. Short overview is here.

  • Original firmware – looks nice but performs poor in 5 GHz range. With both 2.4 GHz and 5 GHz ranges there were performance problems´with LAN connections and router needed restart once per week. The best download speed over wireless N was around 100 Mbps. I tried to configure and make different miracles with original firmware but had no luck.
  • DD-WRT – has more options and features than original firmware, 5 Ghz connections are more stable but performance is even more poor. Wireless N on 5 GHz gave maximum download speeds around 80 Mbps. LAN performance was awful. And again – I tried different tricks to get performance up but again had no luck.

Weird thing I noticed was that home server connected to router with cable had also bad download speed. Depending on router firmware it was either 100 Mbps or 80 Mbps. But my internet connection has 400 Mbps down-stream and I have seen this machine getting 400 Mbps out from that connection when connected directly to ISP provided router.

Asuswrt-Merlin firmware solved my problems

Although I had Tomato and OpenWRT in my waiting list I decided to give a try to Asuswrt-Merlin custom firmware. Some reviews I found from internet concluded that it has very good performance. From screenshots I saw that user interface looks exactly like the same as with original firmware.

Asuswrt-Merlin is an alternative, customized version of that firmware. Developed by Eric Sauvageau, its primary goals are to enhance  the existing firmware without bringing any radical changes, and to fix some of the known issues and limitations, while maintaining the same level of performance as the original firmware. This means Asuswrt-Merlin retains full support for NAT acceleration (sometimes referred to as “hardware acceleration”), enhanced NTFS performance (through the proprietary drivers used by Asus from either Paragon or Tuxera), and the Asus exclusive features such as AiCloud or the Trend Micro-powered AiProtection.  New feature addition is very low on the list of priorities for this project.

Asuswrt-Merlin user interface. Picture is taken from Asuswrt-Merlin homepage.

Before I made my decision to go with it I checked also their Github repository to see if the firmware is in decently active development. There are releases coming. Not very frequently but still it seems to happen on stable manner. So I felt even better to go with it.

After installing Asuswrt-Merlin firmware and configuring the router I made another speed tests. This is what I got with my Surface Book over wireless N on 5 GHz (before firmware change download speed was approximately 90 Mbps).

In total, this is what Asuswrt-Merlin solved for me:

  • download speeds from all machines in LAN are now better than ever,
  • LAN performance is very good – no slow connections between machines in same network,
  • streaming media from home server works smooth now,
  • router doesn’t hung when there is more going on in network (also less errors in system logs).

It’s practically all things I complained about.


For home user it is easy to go with firmware provided by hardware manufacturer but in longer perspective it may not pay off. Although RT-N66U has decent firmware, there are still better and more performant options like open-source firmware built by volunteers and communities. Asuswrt-Merlin is good example how different focus on firmware may save router from going to recycle bin. Before abandoning old router, try out if issues are not coming down to router software. I am sure that my RT-N66U will now server me at least some years more.

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