Orbi WiFi 7 RBE973
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Optimal 5 ghz channel?

mingcyu
Aspirant

Optimal 5 ghz channel?

I used my MacBook to scan and saw that a neighbor was using channel 48 on the 5ghz space. I went to my Orbi 753 and set it to 44 to see if I can get better Wi-Fi results. To my surprise, after setting it to channel 44 and restarting I got about half the internet speed and very high pings on Speedtest. If I set it back to channel 48 it’s back to where it was previously.  My understand is that 44/48 are equals in terms of overlap and bandwidth? Could our Orbis favor one over the other?

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CrimpOn
Guru

Re: Optimal 5 ghz channel?

The Speed Test is:

  • The number reported by the Orbi system (web interface or Orbi app), or
  • Connecting to Ookla Speedtest on the iMac?

The 5G channel setting is far more complicated than one might imagine.  After spending a lot of time searching for a simple explanation, I am more confused than when I began.(When your eyes glaze over, just stop reading and say, "this guy is nuts")

 

To start with, WiFi "channels" have specific radio frequencies.  Wikipedia has a nice description: https://en.wikipedia.org/wiki/List_of_WLAN_channels#5_GHz_(802.11a/h/j/n/ac/ax) 

Here's what it says about channels 36-48 that can be selected in the Orbi app:

CrimpOn_0-1674321328459.png

The green "Yes" indicates that these channels are available to use in the United States.  (The article lists regulations in most parts of the world.)

Notice that each separate channel does overlap with the channel next to it, but those channels are not listed in the pull down menu to be selected in the settings menu.  i.e. only 36, 40, 44, 48 can be chosen and none of them overlap with each other.

 

The issue is that a single channel is only 20Mhz wide. The 750 product's 5G radio is described as:

CrimpOn_1-1674321798501.png

In order to create that (theoretical) blazing 1200Mbps speed, Radio 2 will have to be set to:

  • A full 80Mhz wide radio channel
  • Using 802.11ax encoding at 1024QAM
  • Using 2x2 MIMO (two antennas at the same time)

When using only a single 20Mhz wide channel, the Orbi cannot possibly transmit that full speed, so the "bottom line" is that no what channel the user has selected, the Orbi is going to attempt to use ALL of the channels any time it can.

 

I think that the user channel setting dictates which single 20Mhz channel the WiFi "Beacon Frames" are sent over.  These frames are always sent at the lowest accepted speed so that even the least capable device on the network can receive them.

Beacon Frame Wiki 

 

So, (a) have not answered the question, and (b) have no advice to give. (sigh)

 

 

Message 2 of 4
Phyber
Luminary

Re: Optimal 5 ghz channel?

Interesting. It sort of makes sense but you're correct, it is a tad bit confusing. I just checked my 750 and my M1 iPad Air is showing 5GHz, 1080 Mpbs Link Rate and my M1 MacBook Pro is showing 5Ghz and 1201 Mbps Link Rate. So I guess I'm doing about as good as I can get?

Message 3 of 4
CrimpOn
Guru

Re: Optimal 5 ghz channel?


@Phyber wrote:

Interesting. It sort of makes sense but you're correct, it is a tad bit confusing. I just checked my 750 and my M1 iPad Air is showing 5GHz, 1080 Mpbs Link Rate and my M1 MacBook Pro is showing 5Ghz and 1201 Mbps Link Rate. So I guess I'm doing about as good as I can get?


Those link rates indicate that the two devices support WiFi 5G AX, with 1024QAM encoding and have 2x2MIMO antennas. The difference is probably that one is slightly farther from the router than the other or the antennas are oriented a big differently.

 

None of this explains why setting the "home channel" (my term since I can't find anything describing what the channel setting "means" in the Orbi) would make a difference in a Speedtest or ping.  Those Ookla reports vary from one minute to another depending on network congestion, so it would be intellectually interesting to know if those results are repeatable.

 

It's a challenge for me to mess around with WiFi settings because almost any change results in the WiFi system resetting and my alarm system notifies me "wifi lost".... "oh, wifi restored" with both text and email.  Gets annoying.

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