Avoid using Ethernet with tvOS if DFS Wifi Channels are Used

Avoid using Ethernet with tvOS if DFS wifi channels are used

Normally, when deploying Apple TVs, you want to connect them to the network via ethernet. Like all hard and fast rules, there is one big range of exceptions. According to Apple’s recommendations, Apple TV should be connected to the network over Wi-Fi instead of Ethernet when using DFS channels on the Wi-Fi network and peer-to-peer AirPlay is desired. I still have a big question mark about this recommendation. In our environment we haven’t seen any issues related to DFS channels, however neighboring school districts have.

What’s Different about DFS Channels?

There is an overlap in the 5 GHz band frequencies between what’s possible to use for wi-fi and what certain radar equipment might use. Typically wireless APs listen for certain error frames and will stop transmitting on these channels to avoid interrupting radar signals. Under normal circumstances, you would want to leverage these additional channels in order to allow for more channel separation in wi-fi planning. See Revolution Wi-Fi’s Infographic that gives a pretty decent visual representation of this: https://www.ekahau.com/wp-content/uploads/2018/03/Capacity-Planner-Poster-US-24×36.pdf

Also, According to Wi-Fi Insider:

In some regions, it is important to ensure that WLAN equipment does not interfere with certain radar systems that are the primary users in the 5 GHz band. The DFS feature of the AP software searches for radar pulses in the frequency channel where it is operating, or during the autochannel scan. It constantly monitors errors in the received frames and analyzes the timing patterns for periodicity. If the pattern matches a radar signal, it instructs the WLAN equipment to discontinue operation on that channel as quickly as possible. The WLAN equipment reboots, then begins to operate on another frequency after checking that the new frequency is free of radar signals.

Dynamic Frequency Selection Channels

When a DFS–enabled radio is operating on one of the following channels, the wireless device uses DFS to monitor the operating frequency and switch to another frequency or reduce power as necessary:

  • 52 (5260 MHz)
  • 56 (5280 MHz)
  • 60 (5300 MHz)
  • 64 (5320 MHz)
  • 100 (5500 MHz)
  • 104 (5520 MHz)
  • 108 (5540 MHz)
  • 112 (5560 MHz)
  • 116 (5580 MHz)
  • 120 (5600 MHz)
  • 124 (5620 MHz)
  • 128 (5640 MHz)
  • 132 (5660 MHz)
  • 136 (5680 MHz)
  • 140 (5700 MHz)

Source:List of WLAN channels – Wikipedia

Wi-Fi Insider – DFS  http://wifi-insider.com/wlan/dfs.htm