ED HAYES

My home network is pretty advanced. I have a PFSense home-built router (based on Zotac ZBOX CI323) that connects to my modem, several smart switches (Netgear JGS524E), and 2 wireless Access Points.  The two access points are both made by Zyxel; an NWA1123-AC and an NWA1123-ACv2.  I thought it would be prudent to upgrade the firmware of both devices this week but ran into a problem.

Since both need different firmware, I first downloaded the firmware for the v2 device, and then did the v1 device.  Somehow I managed to download the NWA1121-NI firmware for the v1 device, and then applied it. As I was doing some configuration on the device, I saw I was missing the 5 Ghz settings, which lead me to figuring out I had flashed it with the wrong firmware. I thought it would be easy to revert back since I was able to go one way, but that proved wrong! The device wouldn’t accept the correct firmware.

I did some hunting around the internet, gave up quick, and submitted a technical support request.  Zyxel got back to me the following day saying I would have to RMA the device, sending it back to them, assuming it was in warranty. After some following correspondents,  it was determined that I was out of warranty/support. I turned back to the internet.

I found, on Zyxel’s website (PDF), they had directions on how to have the device pull firmware from a TFTP server before the router fully booted. However, there were some critical steps missing.

• There’s no serial port on the AP; WHAT?
• How do I unzip a bin file? And how do I unzip what comes out of that?
• What software do I use to TFTP?
• What software do I use for a terminal?

Zyxel support insisted that this KB article on their site did not apply to my AP problem, and there was no way I could recover the device without sending it in to them.

I did some more hunting and found someone over at the OpenWRT.org site posted the internal parts of the NWA1123-AC AP, as well as some serial port details. I also found a page for serial port specifics saying I needed a USB TTL adapter.  The same page had details on the pins to connect the adapter to on the AP (see: Router with serial port / header / pins). Turns out Amazon and my local MicroCenter both carried a USB to TTL adapter, for use with RaspberryPi devices. I biked over to MicroCenter, and picked one up.

Once I got home, opened up my AP, connected everything, downloaded and set up Tera Term and TFTPD64, and starting going through the KB article. I used 7zip to extract the contents of the bin file, and the contents of the subsequent file. I ended up with the files shown in the KB article, so even though 7zip said there was extra contents that wasn’t extracted, I figured I was on the right track.

Everything seemed to work great, and got my device flashed with the correct firmware! Sadly, Zyxel’s poor design required me to clear my browser cache to get the AP’s config page working correctly, but if that was the only hiccup, I wasn’t too angry, and I had been stupid enough to flash the wrong firmware on the AP in the first place.

Access Point saved from certain death!