Misadventures in Home Networking (or creating house-wide 2.4 GHz and 5 GHz coverage)

One of the perils of having a large square footage house built in the 1980s is that it is impossible to get WiFi coverage from a single access point. And there is no Ethernet wiring in the walls. This is the tale of how I actually got this problem reliably resolved such that there is decent WiFi coverage in the house and on the two outdoor patios.

Resolving the Cable Backbone (or lack thereof)

Short of pulling CAT6 through the walls, there represents two technologies to create a virtual cable backbone. Powerline Ethernet (which as its name implies uses the electrical wiring) and MoCa (which uses the coaxial cable for TVs). Both offer several hundred megabits of capacity.

MoCa seemed the ideal solution – except that I was unable to get it to work due to IP address conflicts with the neighbors (seriously!). Turns out (from a very helpful upper tier tech at Comcast) that I probably need a MoCa filter as the cable enters the house – and these did not exist in the mid-1980s.

Instead, I used PowerLine networking with hubs/access points in strategic locations going back to my office, where it is patched into a Gigabit Ethernet switch, which in turn is connected to my router. I plan to go back and revisit MoCa once I can source and try a filter.

WiFi Hardware

For the routers themselves, I went with the Asus RT-87 and am using the open source Merlin firmware. The main one is configured as a router, the second and third as access points. IPs are managed by redundant DHCP Servers running on Windows Server 2012 R2. DNS and WINS are both local, though DNS forwarding is going to Comcast’s DNS servers. The reason I went with this approach is, beyond having greater control, DNS is automatically updated so it makes it easy for other devices to find each other on the network. The other custom setting besides WPA2 AES encryption I enabled was dropping signals if less than -70 to force devices to switch access points while traversing the house.

The WiFi Channel Config

Getting the three access points to play nice with other is no mean feat. The reason is that if they are all configured identically, they will be overlapping with each other. So the 2.4 GHz and 5 GHz radios each need to be configured to not broadcast over each other.

The 2.4 GHz Channel Configuration

2.4 GHz channels can be configured to use one of a handful of channels and 20 Hz, 20/40 Hz, or 40 Hz channel widths. 20 Hz channels should be selected unless one only has a single access point, in which case 20/40 Hz should be selected. 40 Hz likely won’t be compatible with many devices. If any 40 Hz channel width is selected, effectively the entire spectrum is then consumed. So, with three access points, the only channels that don’t overlap are:

  • Channel 11
  • Channel 6
  • Channel 1

– making the choice quite simple, with a cap of 3 semi-overlapping access points.

The 5 GHz Channel Configuration (and where it really gets complicated)

5 GHz channels are a bit more complex, as you can configure 20 Hz, 40 Hz, or 80 Hz channel widths along with respective fallback. Using 20 Hz channels makes little sense, as you’d be unable to leverage the higher bandwidth of the newer WiFi standards. The latest AC standard requires 80 Hz channels.

Using a 40 Hz channel width, you can get Channels 36, 44, 149, and 157 on most access points – none of which will overlap. This means you are limited to four access points. If you want to use 80 Hz channels, then you are limited to two access points – on Channels 36 and 149 only.

The other wrinkle is that the 1xx channels are not visible to devices several years old. But since everything here is new enough (2012+ or could use 2.4 GHz), I went with 40 Hz channel width and Channels 149, 157, and 44. At some point, I may explore enabling 80 Hz frames on Channel 149 for the main floor access point (and most used) and then using the other two at 36 and 44.

Parting Thoughts

This was far more complicated to get right than I ever envisaged. at this point, if I need more coverage, I’ll have to get repeaters given channel saturation. And there is not a lot written on how to set this up. Commercial grade WiFi solutions make this easier – such as a Cisco Meraki system – but those cost far more than anyone would reasonably be willing to invest in home WiFi. Eero looks very promising – but is not yet available. So hopefully this helps you if found in a similar situation.