Uap-ac-lr openwrt install

I wanted to share that I have successfully managed to install openwrt 21.02 on uap-ac-lr from unifi firmware 6.2.49 without opening the device.

To keep in short, I have used the "Non-invasive method using mtd-tools from OpenWrt" described here:

Of course, on the first attempt, I was greeted with the message:
can't write to kernel0

But then I remembered that for the u6 the wiki install instructions are stating the following:

#Unlock mtd partitions with some magic:

echo "5edfacbf" > /proc/ubnthal/.uf

I did run the above command and then it worked !

Now the device happily runs 21.02 without needing to be downgraded to 4.3.28 or being opened to use the serial console and tftp.


Hi mihait, and welcome to the community!

That's a great report. Nothing like a little hack-fu

That's not esoteric at all. :wink:

Good find! And you're right, it's documented on the Unifi 6 LR page, but not the Ubiquiti UniFi AP AC page.

Perhaps you'd consider requesting a wiki account and documenting your results on the right page. This was how I first started contributing. Wiith 1600 or so supported devices, the device-specific pages are often lagging reality. They need good device evangelists to help keep them current.

What are your plans from here? Do you intend to remain on 21.02, or move ahead to 22.03 or even the new 23.05 which is now in the release-candidate stage?

Thank you!

I can do that but I think it would be wiser to have someone else test it and confirm the finding before requesting the edit.

I intend to stay a bit on 21.02 and then upgrade to the latest stable.
Also I intend to flash the router as well with openwrt :slight_smile:

Always a good thing - you never know when someone else will come along though, and the next person may need the benefit of your experience, so I've taken the liberty of putting a note about possibly requiring it on the page.

Great idea! Look forward to reading about your success with that too.


I also successfully loaded OpenWRT to a Unifi AC LR using this method.

Unfortunately, I only seem to be able to auto negotiate eth0 at 100mbps to my gigabit switch?

Have flashed up to 23.05.3 just now but still not getting gigabit.
ethtool eth0 states both ends are capable of gigabit.
Tried various cables.
Also added "Atheros L1 Gigabit Ethernet support" package through LuCI System>software as it sounded hopeful :slight_smile:

Did you happen to verify that the AP was properly negotiating a 1Gbps link when it was using the vendor firmware?

Also, how are you getting PoE to the device -- are you using a PoE switch or a PoE midspan injector? If the latter, what injector are you using -- brand and model? Some of the Ubiquiti injectors are not gigabit (if you've got the original adapter that shipped with the AP, it will be gigabit; but if you happened to buy it used or if you have a bunch of PoE injectors around, it's possible you've got a 100Mbps one).

Unfortunately I can't confirm 100% that the AP was connecting at gigabit with the stock firmware.

It is however using the matching unifi poe injector for the AP.

I do have another AP exactly like this and that is connecting at gigabit (stock firmware)

If anyone has any other ideas please let me know, otherwise I'll be swapping around Poe injectors and trying to roll back to stock to confirm.

Swapping the PoE injectors would be a good sanity check. Are they both the same model injector?

EDIT: In fact, if you can swap the APs entirely, that might be a good way to check the entire stack. If the OpenWrt one connects at gigabit at the other location and the stock unit falls to 100Mbps, it suggests that there is a problem with the cabling, injector, and/or ports on the switch.

Aha you were right thanks @psherman

The PoE injector I had been given with this AP was only rated at 100mbps.
POE-24-12W = I have
POE-24-12W-G = I need
Swapping them around brought up a gigabit link on the switch with the OpenWRT flashed AP.

Thanks for your help in getting to the bottom of this. Now I have to try and get this PoE injector sorted out...

Glad I could help!

If you're in the USA, the gigabit PoE injectors from UI are like $10, so pretty cheap (although add shipping and that might double the cost!).

Take a look at the bottom (or top, depending on your perspective) of the APs and look to see if they have 802.3af on the label -- if they do, they'll work with standard 802.3af PoE switches and injectors. Otherwise, you need to get a 24V passive injector like the ones you have. If you can use 802.3af, you might consider a PoE switch instead of the injectors.

If your problem is solved, please consider marking this topic as [Solved]. See How to mark a topic as [Solved] for a short how-to.
Thanks! :slight_smile: