Quick Network Fix with WiFi Explorer

Quick Network Fix with WiFi Explorer

A month ago or so I visited a school on a Hutterite colony to have a look at their wireless network. The school division I work for partners with this colony on some of their technology and other parts of their school system. The complaint was “the WiFi hasn’t worked in the library all year”. That was easy enough to fix – as soon as we walked in, we noticed that the status LEDs on the AP right outside the library were orange. It had been like that for eight months, and nobody questioned it or called. A quick power cycle via the POE switch and the AP was back up. That wouldn’t be much of a blog post though.

I had just gotten my new 15″ MacBook Pro, and this was a perfect opportunity to fire up WiFi Explorer by Adrian Granados (@adriangranados). I had heard nothing but good things about this app. It really is a steal at $16.99 CAD or $14.99 USD and has a ton of useful features. I especially like the Advanced Details feature, which allows you to dig into a beacon and learn what the network is capable of. If you are thinking about getting a MacBook, check out these posts by Glenn Cate (@grcate) and Craig Schnarrs (@the_wifi_guy). They cover pretty much everything you need to know.

I should note that I *HAD* some images to use with this post, which were mostly screenshots from that day. Unfortunately I had a weird issue with the MBP and had to reformat and reinstall before I had a chance to get a drive for Time Machine. The display started flashing black, and performance was basically at a standstill. The Google had surprisingly little information for me so I had to reinstall. I have been storing MOST of my stuff on Google Drive but I guess I brain farted that day. Lesson (that I’m pretty sure I’ve learned a few times already) learned.

Anyways, WiFi Explorer showed our APs as expected, as well as an SSID “Linksys” on channels 11 and 149+153. Here is a copy of the floor plan, with the Linksys AP location indicated with the L. Please note this is NOT my design.

New Doc 3_1

The library that was initially having problems is the bottom right room marked “Kathy’ Room”. The Linksys is in the Photocopier Room. It’s only used when the head guy needs to bypass the colony’s filtering for testing, so it wasn’t worth my time to track down passwords, etc.

Our Juniper APs were all set to auto channel and power with both radios enabled. I’m not a fan of the way Juniper’s automatic stuff works, so on my network I choose to go with static settings and constant vigilance. The only problem is I don’t have remote access to this school, so monitoring is not possible. Constant vigilance turns into assuming they’ll call if performance degrades. Because of the Linksys on channel 11, my four APs had all selected either channel 1 or 6 in 2.4 GHz; two were on channel 1 and two were on channel 6. I can’t remember which were on which. The first thing I did was disable the 2.4 GHz radios on APs 2 and 3. With only two of my own APs needed in 2.4 GHz, I didn’t mind that the Linksys was BLASTING away on channel 11. This school uses all Apple devices (iPads and MacBook Airs, around 30 in total) so I knew they would prefer the 5 GHz band anyways. A quick check in a few locations with WiFi Explorer showed that the signal strength in 2.4 GHz from APs 1 and 4 was satisfactory. Again, I had images but…argh.

Here is what the final configuration looked like. Note that APs 2 and 3 have their 2.4 GHz radios disabled, although the GUI doesn’t show it for some reason.

decker post change

My logic was as follows:

  • I went with 40 MHz channels mainly because I could. This isn’t a high-density deployment, and the students probably move some large files around the network.
  • Transmit powers are roughly matched to the network devices, maybe a little lower. In the case of APs 2 and 3, that is the max power for that model (WLA522) in that frequency band.
  • I put the lowest TX powers on the APs that had the smallest areas to cover.
  • AP 4 is in the early years’ end of the school and will see the fewest clients and least usage, so I didn’t mind having it contend with the Linksys on 149+153. The Linksys will pretty much only beacon, and when it is used, it is unlikely that any students will be in the school. They should unplug it, but that’s not my call.

So far the phone hasn’t rang, although it is now summer holidays. I’ll probably visit just before school starts and see how things look, and reboot any APs that have hung themselves.

Thanks for reading!