Friday, November 20, 2015

How To Neutralize Your Home Network

I'll begin by saying this is not a review of the Infant Optics DXR-5. Not directly, anyway. While it's a fine baby monitor, and one I am happy with overall, there's one thing that people should be aware of if they're wondering how a video monitor relates to other wi-fi enabled gadgets in the home. It's not something you want to find out the hard way.


Like most homes, we depend pretty heavily on the 2.4 GHz wireless spectrum. Wi-Fi, 802.11b/g specifically, lives here, as do some bluetooth devices, cordless phones, RF remotes and even your microwave. Unless you're a speed demon superuser or actively trying to avoid it, you'll probably be spending a lot of time connected to 2.4 GHz. 

This describes my house pretty well. We have a mix of old and newer devices - laptops, tablets, phones, game consoles, streaming devices, etc. All of them can access wireless b/g, about half can get on wireless n (5 GHz) and I'm fairly sure I don't own anything that is capable of running wireless ac. My router doesn't support ac anyway, so that's somewhat a moot point.

Our router, a TP-Link WDR4300, is a midrange piece that has decent administrative features; the ability to isolate channels, set device priority and other things most people won't screw with. When I first set it up, I put all the 2.4 GHz traffic on channel 11 to avoid potential interference with my neighbors, who appeared to be camped out on 1. 

I didn't think much of this after that was done, and then into this 2.4 GHz stew we added the DXR-5. When we started using it, we noticed near total blockage of everything on 2.4 GHz. I checked channel interference again and didn't see anything coming from the monitor, so I figured it wasn't the issue. Over the span of 3 weeks, I called my ISP about 4 times, tried a wireless repeater, moved the router around and did a bunch of other maddening things, none of which made any difference. 

After one particularly illuminating google-session, I discovered the DXR-5 uses a technology called FHSS, or Frequency Hopping Spread Spectrum. This allows the device to randomly jump between channels in an encrypted pattern known only to sending unit and receiver. The monitor is effectively on any and every 2.4 GHz channel at any given time, which will definitely play hell with anything else utilizing 2.4...d'oh! I do see how this is a benefit and desirable for a baby monitor, as you'd probably want to make sure the video feed is stable at all times. 

Infant Optics says to try channels 1 or 11 to minimize the effect of this, as you're slightly less likely to find interference at the edges of the spectrum. This didn't make much difference, as I was already on 11 and getting blacked out. For my purposes, I switched anything that could use wireless n to the 5 GHz band and hardwired things like my Xbox (which you probably want to do anyway for optimal connection). I also picked up an inexpensive b/g/n USB dongle for the lone laptop stuck on 2.4 GHz. 

Mostly the issue has been solved, as I've effectively moved everything off of 2.4 except the monitor itself. But this may not work for everybody, especially if you rely on, say, an older tablet or cell phone that can't access 2.4 GHz and your problem can't be fixed via dongle. 

One thing I couldn't work around was our printer, which is wi-fi enabled but doesn't have wireless n. So for now we just have to connect via USB when we want to print. Annoying, and hardly convenient, especially since we could print wirelessly before. 

Anyway, my takeaways from this experience are:
  • Make sure you read the fine print when it comes to video baby monitors and your home network. If you have a mix of old and new devices, you could be creating a real headache for yourself.
  • If you want to effectively shut down someone's 2.4 GHz WLAN, just plug a DXR-5 in somewhere in their house and don't tell them. 

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