Help Me Understand What's Going On With Wireless Diagnostics - 3 MacBooks With Conflicting Results

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Help Me Understand What's Going On With Wireless Diagnostics - 3 MacBooks With Conflicting Results

Note that I live in Thailand.

The devices involved here include a 2010 MBA, a 2010 MacBook (White), a 2017 MBA, a Raspberry Pi 4, an old AirPort Extreme (the flat one), an Apple TV 4, several iPhones and iPads, a "smart" Samsung TV and a single HomeKit enabled plug.

I have a condo which I visit about monthly for five or six days at a time. The Pi and the 2010 MBA run 24/7. Their main task is to capture and upload webcam images to a web host and to encode time-lapse videos daily and upload those to the web host. These machines also perform other periodic tasks including keeping the Internet online (the router is behind a captive portal), monitoring bandwidth, and more. This has all worked very well, with flew glitches, for several years now.

The webcam images and videos are here: https://www.mgnewman.com/chaam.php

The condo provides a single private (non-routable) IP address to each unit. I have set up the AirPort Extreme to distribute private IP addresses in a different subnet to local machines. This creates a double NAT condition which works OK but which requires an SSH Tunnel for remote access.

The MBA stopped uploading photos on January 30th. The Pi continued. I was unable to log in to the MBA remotely, but I could log in to the Pi. From the Pi, I was unable to ping the MBA. I concluded that the MBA had either frozen or crashed.

When I arrived at the condo on February 11th I was surprised to see that the MBA was up and running, but not connected to WiFi. The WiFi icon in the menu bar was greyed out and no SSIDs were listed in the drop down menu. I was able to connect by going to the Network pane in System Preferences. I rebooted the MBA and reset the PRAM. Upon reboot the MBA connected to WiFi automatically which it is set to do in the Network preferences.

In order to find out what was up I decided to run Wireless Diagnostics. The first thing I looked at was the "Assistant", which told me: "You are connected to a Wi-Fi network that cannot communicate with your wireless router." And yet, at that very moment, the MBA was indeed connected to the router via WiFi, was connected to the Internet and was able to examine the Airport's configuration using the AirPort Utility.

Question: What, exactly, does Wireless Diagnostics mean by: You are connected to a Wi-Fi network that cannot communicate with your wireless router.

I decided to dig a little deeper and looked the Wireless Diagnostics report. This report contains numerous files. One of the files is called condoMGN-diagnostics.txt (condoMGN is the SSID of my WiFi network). That file contains the line:

09:13:11.870 No Scan Results 0.000 Yes No Wi-Fi networks are visible

Another file, wifi_scan.txt, contains the following line:

total=6, 5GHz=2, 2GHz=4, ibss=0, hidden=0, passpoint=0, airport=4

Indicating that a WiFi scan found six WiFi SSIDs. It then goes on to give details of the four found networks.

Question: Why does one of the Wireless Diagnostic reports say that no Wi-Fi networks were visible while another report goes on to list the six networks that it found?

At that point I was more confused than enlightened. I didn't find anything in the voluminous reporting to tell me what I needed to do to make sure the old MBA would automatically connect to the WiFi network, as needed.

I then decided to run Wireless Diagnostics on the other two MacBooks; the 2010 White MacBook and the 2017 MBA. Note: The old MBAs are running High Sierra and Wireless Diagnostics version 1.0, build 805. The newer MBA is running Catalina and Wireless Diagnostics version 1.0, build 901.

The white MacBook gave me the same answer from the "Assistant": "You are connected to a Wi-Fi network that cannot communicate with your wireless router."

The 2017 MBA gave a completely different assessment: "Your Wi-Fi connection appears to be working as expected."

Question: Why does the Wireless Diagnostics on the newer MBA tell me that the network is fine while on the older MBs tells me that they cannot communicate with the router?

At that point I pretty much gave up. Everything was working. The old MBA was uploading photos as usual. Time to give up.

Just as we were getting ready to leave the condo on February 17th there was a very brief power outage. The AirPort Extreme rebooted. After a few minutes I checked everything. All the iPhones and iPads and the Raspberry Pi and the Apple TV had immediately and quickly reconnected to the WiFi network. None of the Macs connected automatically. On each MBA I turned WiFi OFF and then ON and then it automatically connected.

Question: What could cause all the MacBooks to fail to connect automatically when all the other devices on the networked were able to do so all by themselves?

Clearly, there is something seriously wrong; something that didn't exist until early this year. I remain clueless.

MacBook Air 11″, macOS 10.13

Posted on Feb 18, 2021 2:47 PM

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Answer 1

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Buadhai Author

Level 1

70 points

Feb 18, 2021 6:15 PM in response to LaPastenague

Thanks for the explanation. I wondered about the double NAT causing that odd message. I'm sure you're correct.

I've lived in Asia most of my adult life and have been dealing with various UPS most of that time. I have one here at home, but I hesitate to stick one in a remote location. At the moment my thinking is to replace the old MBA with a Raspberry Pi. They recover well from power outages and seem to reconnect to the router without difficulty. I hadn't thought of removing the battery from the MBA. In fact, I just put in a new one in December (the second replacement). With the battery out, will it restart after a power outage? I do know that after a long power outage that completely depletes the battery, the MBA will not restart when power resumes. You need to hit the power key.

In the mean time I have written a tiny shell script that checks the Internet connection. If it's down, it cycles the WiFi OFF and then ON. I'm hoping that will cause the MBA to reconnect after a power outage.

Aside: I lived on Saipan for many years. When I moved into a new office there, I had an entire room dedicated to a giant UPS that had 36 lead acid batteries. Trouble is, there was no room in the budget for replacement batteries. When it was time to replace them I had no choice but to shut down the UPS. I was told to auction it off. No one bid. I gave it away. (And, yeah, I was working for the US Government.)

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Answer 2

Buadhai Author

Level 1

70 points

Feb 18, 2021 11:01 PM in response to LaPastenague

AFAIK, the MacBooks don't have the option to restart after a power outage. Maybe it appears if you remove the battery. The desktop Macs do have this option.

Here's a screenshot of a 2009 Mac Mini's Energy Saver CP under El Cap:

And these screenshots from a 2010 MacBook running High Sierra:

I've really wrestled with this problem. If a MacBook is shut down by running out of battery power, it won't start up upon power resumption. If you set a schedule for "Startup or Wake" it will start on schedule after a command shutdown, but not after a battery drain shutdown.

The bottom line is that a MacBook is a poor choice for a remote computer that you want to keep up 24/7. The Pi is a much better choice.

Thanks again for your help.

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Answer 3

Feb 18, 2021 4:41 PM in response to Buadhai

"You are connected to a Wi-Fi network that cannot communicate with your wireless router."

I suspect this is just double NAT.. because the router it can see (airport extreme) only has a private IP it cannot connect to the main building router. This is not a surprise and pretty much standard.

The later machine ignores the double NAT which is really what it should do.. Lots of guesswork as Apple doesn't give enlightenment to the masses.

Just as we were getting ready to leave the condo on February 17th there was a very brief power outage. The AirPort Extreme rebooted. After a few minutes I checked everything. All the iPhones and iPads and the Raspberry Pi and the Apple TV had immediately and quickly reconnected to the WiFi network. None of the Macs connected automatically. On each MBA I turned WiFi OFF and then ON and then it automatically connected.

This is the bigger issue.

I would definitely put a UPS into the system to maintain power to all your required equipment not battery powered.

Dropouts on routers cause serious issues. In fact short drops are more serious that lengthy failure because it can lock up the router. The problem is the laptop's battery would prevent it restarting so it depends on how long it is set to wait for Internet dropout before it starts attempting to find the network again.

The question about the laptop which happened to three different machines of different ages is interesting but not one I know a lot about.. A quick search shows lots of people have issues with internet disconnection after a power failure. Plus no one seems to have a decisive this is what is wrong.. here is settings to fix it.. If you have issues with reconnection failure with UPS just running the router and pi it might take more drastic action so you can reboot the laptop as well.

I would be inclined to remove the laptop battery (not so easy in Apple world i know) so the laptop also runs on the UPS.. and a failure of power after say 1 hour would cause everything to shut down properly so it can reboot properly.

BTW.. just thinking out loud.. One thing I would do is set the IP on the laptop to static. Setup the airport to have a static IP in reservations. That does help loads when things collapse. I would also make sure for dns you have both Airport and one public address in the laptop.

The laptop might actually be connected to wifi but not passing packets to the router because the DHCP is fouled up.

I lived in Malaysia many years ago. UPS was absolutely essential for use on computer gear. Power was very iffy.

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Answer 4

Feb 18, 2021 10:14 PM in response to Buadhai

With the battery out, will it restart after a power outage?

You can set the Mac to restart after a power outage.. without the battery it should do exactly that.

I think using a pi for the task is great idea if you don't need the power of the computer. Keeps things working a lot longer if power does dropout.

It sounds like you have loads of experience with these things.. it is always hard to guess where people are up to.

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Help Me Understand What's Going On With Wireless Diagnostics - 3 MacBooks With Conflicting Results

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