Mac Pro Mid 2010 5,1 wifi 5GHz: no 36 40 44 48 channels

I finally found the problem! After reading this article it dawned on me. The author describes the exact problem I have in my home network. Amazingly, by solving this seemingly unimportant issue, I found the key to another -- 6 year long nagging and utterly frustrating -- WiFi issue I have in our home.

Here is how it works:

• When a Mac is booted or wakes up from sleep, if WiFi is on, it scans for available network SSID's
• The first SSID it encounters emits beacons containing its country code
• The MacBook (mobile devices can travel to other countries) conforms to the country code of the router (routers generally don't travel)
• According to the country code settings some channels may or may not be available
• In our home we have an Omnik solar inverter, the WiFi of which is established by setting up an AP by the Omnik itself which in turn connects to the router after configuring the right settings
• The Omnik WiFi module is set to country code TW (Taiwan) and emits beacons at 2.4GHz
• When our MacBooks wake up from sleep, scan and find the Omnik first, the CC will be set to TW and 36 40 44 48 channels are dropped

You can check the screen shot in my OP, CC is TW. Thank you for providing the links above, I found that only the macOS built in Wireless Diagnostics tool will actually display the country code, so this was very helpful!

I recently went 5GHz only in my home network. 5GHz signals carry less far than 2.4GHz so the Omnik now wins lots of times and then macbooks fail to reconnect.

Mystery solved!

Now trying to contemplate a solution approach...

Hi BDAqua, I got it! 5GHz connections on both my 2008 Unibody Macbook Dual Core and my Mid 2010 Mac Pro. I knew I had seen it and it wasn't a dream :-)

I had some network issues before that were solved by switching off IPS (UniFi Intrusion Prevention System). Somehow these Macs are now listening to the 5GHz broadcast and even in System Info the 36 40 44 48 bands are listed where they weren't before.

Could add screen shot if you like...

Regards,

Peter

That sounds plausible thank you. Meanwhile I’ve been troubleshooting a similar issue concerning a late 2008 MacBook unibody dual core.

After a thorough home WiFi redesign, where I took out all 2.4GHz channels so now 5GHz exclusively, that 2008 MacBook has been hit n miss reconnecting.

• It did in fact connect initially so I thought all was well
• i checked it was a 5GHz connection
• i checked it was the AP BSSID I expected
• after that, Reconnecting was not consistent
• system info reads same channels as Mac pro so no 36 40 44 48
• From my UniFi router Control paneI I read it has in fact connected occasionally to 5GHz on channel 44! How can this be if 36-48 is not in the supported channels list on sys info?

My current preliminary solution is to (reluctantly) re-add a single 2.4 channel on one AP so the (apparently almost legacy) 2010 Mac Pro and 2008 MacBook do connect instantly.

Still I wonder what’s going on with that 2008 MacBook in fact connecting to channel 44 which is not in the supported channels list

any clues?

thanks!

Thank you for your quick reply! Your analysis sounds very good. However, I have been able to actually get some throughput using that 5GHz channel 44 connection, i.e. I have been able to load web pages and sync email.

Here is a Unifi controller screen shot, indicating that the machine has been connecting to both 2.4 GHz and 5 GHz channels, including the amount of data exchanged:

oh I’m very sorry to hear that. Well the point of the image is that UniFi reports that the 2008 MacBook has had multiple connects at channel 44 and has in fact transferred data, despite the fact that this machine doesn’t list ports 36-48 in system info as available.

Okay, thanks. You're a level 10 poster so if it's new to you, I am going to dig further. There have also been 2.4GHz connections in the past, so for all I know the data transfers on channel 44 were in fact just handshakes gone bad.

The connection duration varies from 0 to 14 minutes and the data exchanged goes from 100 bytes to over 4 megabytes.

Before I can say for sure that this machine actually has network throughput on channels 36-48 I will test once more by switching off the 2.4 band and wait for it to connect And when it does, try to load some web pages.

I'll keep you posted.

I tried to lure the 2008 MacBook into snapping on 5GHz channel by switching off the 2.4. No dice. I even created a new 5GHz SSID but the WiFi lists 2.4 Options only. I am uncertain now what I’ve been seeing the other day. But so far you are right and it won’t work. if ever I notice it does I’ll get back here :-)

Well, yes glad it works. But the real question is why it didn't before. Do you know of a macOS networking software approach that lists available channels depending on the BSSID's that are available from the router? Is this behaviour as designed?

Thanks! The question now is, how to solve the issue. So whenever the CC changes to TW -- due to the Solar inverter AP being the first AP received after wake -- channels 36, 40, 44, 48 and 52 are unavailable. Thus, I need to find a different channel that is in fact available despite the issue.

So I'm currently experimenting with DFS channels. Our living room AP I set to a fixed channel of 56, our loft I set to 100. Are there any drawbacks to this approach, aside from the hypothetical possibility that a weather or governmental signal pops up as the result of which the AP switches off for a while or tries a different channel? I mean as long as I have a stable connection, wouldn't this be a good workaround?

Thanks.