Channel 1 + 2 not visible

RouterOS Wireless Networking
1

Hi All,

after finally acquiring two RB hap ac (used), I have set them up as access points in my home. Following best practice, I wanted to set one to use wifi channel 1 and the other to wifi channel 11. After doing so, I found that I could no longer “see” the network on channel 1 using both my MacBook Pro and my phone (Samsung Galaxy S10). After some playing with it, it seems that for some reason I cannot use channel 1 and channel 2 with those devices. Setting it to channel 3, I can suddenly see the network and also connect to it. The funny thing is that other devices (Sonos, Amazon Echo, Kindle, …) can connect, even on channel 1, so I am wondering what might be keeping my higher-end devices from connecting on channels 1 + 2. Any ideas?

TIA!

Cheers,

Smoerrebroed

2

Why not share your wireless setup config?
In “New Terminal” type "interface wireless export hide-sensitive ", and post the output here in a code-box.

Otherwise all of us just have to imagine what could be the reason … there are too many parameters to guess.

3

Of course:

set [ find default-name=wlan1 ] band=2ghz-g/n channel-width=20/40mhz-XX country=germany disabled=no distance=indoors frequency-mode=regulatory-domain installation=indoor mode=ap-bridge ssid=homenet station-roaming=enabled wireless-protocol=802.11 wps-mode=disabled
set [ find default-name=wlan2 ] band=5ghz-a/n/ac channel-width=20/40/80mhz-XXXX country=germany disabled=no distance=indoors frequency-mode=regulatory-domain installation=indoor mode=ap-bridge ssid=homenet5 station-roaming=enabled wireless-protocol=802.11 wps-mode=disabled
/interface wireless security-profiles
set [ find default=yes ] authentication-types=wpa2-psk mode=dynamic-keys supplicant-identity=MikroTik

Again, only changing the frequency from 2422 to 2417 or 2412 will make the AP invisible to my MacBook and my Android phone while other devices can still see it and connect to it. Also, I tried with two other APs I have lying around (TP-Link, Netgear), and with those I can also see the SSID and connect when they are set to channel 1 (or 2).

4

This is what I was looking for (among others) … “channel-width=20/40mhz-XX” , while this is not necessarily a problem.

With the XX you don’t know if the Ce or eC is used, that is if the extension channel is to the lower frequencies or to the higher frequencies. But actually MKT has no choice here, it must be Ce , or the channel would be lower than 1. Mikrotik is not using center frequencies for the wider channels.
Nevertheless don’t forget that the channel 1,2,3… are only 5 MHZ apart, so setting 20/40 MHz Ce width is taking 8 channels. (0),1,2,3,4,5,6 (and half of -1, and half of 7)
Setting channel 2427 (3) Ce would be 2,3,4,5,6,7,8 (and half of channel 1, and half of channel 9). It’s the same as 2442 (7) eC.
https://en.wikipedia.org/wiki/List_of_WLAN_channels#/media/File:2.4_GHz_Wi-Fi_channels_(802.11b,g_WLAN).svg

I see nothing wrong here, so can’t help you, but your clients when set for 20/40 may be different in using frequencies.(eg. using real center frequencies)

5

Alright, looks like that was the issue! I had actually assumed that MikroTik would automatically “know” that it shouldn’t go below channel 1, but apparently it doesn’t and will somehow favor eC against Ce. Setting it to eC (fixed) will still show the same problem whereas choosing Ce does make the network appear on all devices. Thanks for that hint! :slight_smile: