Visible SSID considered hidden by iPhone

Hello everyone,

Newbie here. After installing OpenWRT in a Zyxel WSM20 Multy M1 (see OpenWrt for Zyxel WSM20 (Multy M1) discussion - #680 by N2OWrt), I was struggling to set up some wireless networks...
Now, the issue is about one (AX, 5 GHz only, WPA3, Channel 132, 80 MHz), which has a SSID visible for a Win10 PC, but it is considered hidden by an iPhone (when manually entering SSID + password, the iPhone connects, but it cannot do that automatically). In the general setup of the interance configuration, "Hide ESSID" is not selected (actually, I have tried to enable and disable, but the iPhone could not see the SSID in both cases...).
It is not clear to me why the wireless network behaves like that. Any hints? How to make the iPhone connecting automatically to that network? I may understand that the issue could come from the iPhone (since Win10 seemed happy with the router settings), but I would like to understand if there is any parameters of the router settings that could help.

Thank you in advance for your help

you are saying in chanel 36 could.not be seen the essid, why so?

maybe iPhone cannot probe on that channel.

there are variables open, maybe his iphone have outdated OS and since is a closed source os it is hard to define bugs easily, i would recommend to try to shut down and turn on the router after any changes , so he could systematically find out

well we need him to replay.
even if I do not like iPhone, that devices do not have this kind of bug. it's about radio rules. I'm just saying. he need test that.

In general, 36, 40, 44, and 48 are the best 5G channels WiFi because they are least likely to overlap with other channels. However, if these channels are already congested in your area, you can try using channels 149, 153, 157, and 161 as they are also less likely to overlap with other channels.

5 GHz wifi uses a variety of channel widths allowing 20MHz, 40MHz, 80MHz, and 160MHz, unlike 2.4GHz which allows for only two channels’ widths (20Mhz and 40Mhz). The 5 GHz wifi channels also supports the IEEE 802.11a /n /ac networking protocols. The higher frequency combined with ultrawide channel width plus the latest 802.11ac standard makes 5GHz wifi channels best for high-speed wireless networking.

However, there is a downside to the 5GHz spectrum. The higher frequency also means it is less susceptible to obstacles and has a shorter distance span between the transmitter and receiver.

who told you that, I'll stop here because we are off topic. under OpenWrt I use channels that you cannot even imagine,for my wireless Security. I do not even use a password on some devices.

Channels we cannot even imagine!? How is that supposed to work!?

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i was referencing about your comment of the possibility of it being a channel problem, that is why

The issue is likely that in most countries 132 is a DFS channel, while 36 is not. DFS channels are shared with weather radar systems and it is important that wifi not transmit when there is a radar station in the area.

In OpenWrt make sure your country code is set. If it is a dual radio device set the same country on both radios.

I think that by default this causes the AP to broadcast the country code in beacon packets, which should make a client such as an iPhone follow the proper country rules.



Country code is set correctly (for both radios, even though only 1 is on, the one providing the AX wifi).
Channels until from 32 to 112 were crowded (about 20 SSIDs), which is why I tried with 132, just to avoid overlapping, no other special reason. But if there is a certain selection of channels to avoid, please let me know. I thought that I had a free choice, since there was no warning after setting the country code ...

Iphone is up to date (iOS version 16.6)

Thank you

maybe @frollic and @psherman would help you

When I experimented with SSID names, I Found that using some characters caused one of my devices to not see/list the SSID. I think I saw an issue doing a copy/paste where a NULL char got pasted or it might have been a space or non-binding space etc.

If the SSID in question is not just using simple alphanumeric ASCII characters, try adding/changing the name on the same channel to something simple with characters in the range [a-z,A-Z,0-9] as a test. If it works, then try adding any desired additional characters one at a time, including unicode characters until you find the offending one and work around it.

be simple, can iPhone see the essid on channel 36?

it is already the case. Anyway, see below post ...

Thank you for your hint @spence


What I discovered this morning (after I switched off all the devices = router / iPhone / PC last evening): both the PC + iPhone have connected without issues. I will monitor in the next days if it continues like that, and then, I will marked the thread as solved.

I guess @froyic provided a good suggestion:

I would mark his post as solution, if I see that in the next days everything is fine.


@froyic was mentioning @frollic and @psherman ... if you have any recommendations, please let me know, I do not want to cause any issues to radar stations as @mk24 said

Thank you all for your support and efforts


I don't really have any recommendations here beyond these:

  1. Make sure you're up-to-date on your iOS version as well as OpenWrt.
  2. I recommend 40MHz for general performance (you don't get the best speeds, but you should get pretty solid performance overall).
  3. look at the list of wifi channels and ensure you stay out of the dfs channels.
  4. Try forgetting the network on your phone and then restarting the device. Does the network show up when you use the wifi browser?
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Hi @psherman,

  1. Then I will set to 40 MHz.
  2. Where can I check about Dynamic Frequency Selection (DFS) / TPC? From the Wikipedia page, column for "Europe", it must be with TPC or DFS or both, for all the channels below 140... and if I want to avoid DFS, it should be below channel 48 (area already crowded, from what I could see from the channel analysis)
  3. Tested, and the phone could reconnect after restarting. The network was visible

Thank you

Can you please explain to me what are the advantages (reliability, I guess?)?
I made a quick speedtest, I can see a noticeable drop of download / upload speeds (although good enough for my needs, average values were over 150 Mbits vs 200 before, out of a connection with a nominal 300 at the ISP router)

Thank you in advance

try 80mhz for best speed, altrough 40mhz aims for stability, 80mhz bandwidth aims for speed