Yesterday my Wi-Fi on this iMac went off.

No way to connect it to my router.

I could see other (familiar) neighbor's routers.

Fired up iStumbler - usually I'd see a dozen or more local WiFi's over 2
bands. Now only seeing a few at a time.

Did all the usual stuff. The names of the routers would change from
time to time.

Occasionally it would connect to one of my 4 WiFi spots (2 private + 2
guest). No internet traffic.

Reviewed and reset everything.

Removed and restored the WiFi from Preferences.

"Make Service Inactive" - reboot - "Make Service Active".

SMC reset
PRAM reset

Briefly today, one of the guest WiFi's worked for about 10 minutes
before dropping out again.

<sigh>

Took the iMac screen off (this is the slim edge edition - I never
re-sealed it after a disk change, so just removed the packing tape that
was holding the screen on....)
Disconnected and removed the display.
Disconnected the RF connectors, examined them - fine, restored.

Unscrewed the antennas from the edges, examined, cleaned (in case of
metal particles).

Noted that the grounding "fingers" that bond <cough> the backshell to
the display assembly around the main electronics could potentially touch
the antennas. Put Kapton tape in between to make sure there would be no
contact when the display "pressed" these in again.

Re-assembled.

Still no Wi-Fi other than a brief burst of 2 or 3 minutes on a guest access.

Deleted a pile of related files in
/Library/Preferences/SystemConfiguration/ (per a guide online) and
re-booted.

The behaviour smacks to me of failing WiFi hardware - the intermittency
of known WiFi access points appearing and disappearing.

At first thought the antennas or cables - but they are fine as far as I
can see.

No bluetooth issues - but not sure if it's the same chip. From the h/w
config I don't believe so. (Both are Broadcom).

Any ideas appreciated.

I'll try a Safe Mode boot tomorrow evening.

--
“If you torture the data long enough, it will confess to anything."
-Ronald Coase

On 26/06/2023 02:07, Alan Browne wrote:
> Yesterday my Wi-Fi on this iMac went off.
>
> No way to connect it to my router.
>
> I could see other (familiar) neighbor's routers.
>
> Fired up iStumbler - usually I'd see a dozen or more local WiFi's over 2
> bands.  Now only seeing a few at a time.
>
> Did all the usual stuff.  The names of the routers would change from
> time to time.
>
> Occasionally it would connect to one of my 4 WiFi spots (2 private + 2
> guest).  No internet traffic.
>
> Reviewed and reset everything.
>
> Removed and restored the WiFi from Preferences.
>
> "Make Service Inactive" - reboot - "Make Service Active".
>
> SMC reset
> PRAM reset
>
> Briefly today, one of the guest WiFi's worked for about 10 minutes
> before dropping out again.
>
> <sigh>
>
> Took the iMac screen off (this is the slim edge edition - I never
> re-sealed it after a disk change, so just removed the packing tape that
> was holding the screen on....)
> Disconnected and removed the display.
> Disconnected the RF connectors, examined them - fine, restored.
>
> Unscrewed the antennas from the edges, examined, cleaned (in case of
> metal particles).
>
> Noted that the grounding "fingers" that bond <cough> the backshell to
> the display assembly around the main electronics could potentially touch
> the antennas.  Put Kapton tape in between to make sure there would be no
> contact when the display "pressed" these in again.
>
> Re-assembled.
>
> Still no Wi-Fi other than a brief burst of 2 or 3 minutes on a guest
> access.
>
> Deleted a pile of related files in
> /Library/Preferences/SystemConfiguration/ (per a guide online) and
> re-booted.
>
> The behaviour smacks to me of failing WiFi hardware - the intermittency
> of known WiFi access points appearing and disappearing.
>
> At first thought the antennas or cables - but they are fine as far as I
> can see.
>
> No bluetooth issues - but not sure if it's the same chip.  From the h/w
> config I don't believe so. (Both are Broadcom).
>
> Any ideas appreciated.
>
> I'll try a Safe Mode boot tomorrow evening.

Hello Alan

It seems like you have already performed several troubleshooting steps
to resolve the Wi-Fi issue on your iMac. If the problem persists, here
are a few additional suggestions you can try:

1. Safe Mode: As you mentioned, booting your iMac into Safe Mode is a
good idea. It helps to isolate software conflicts that might be
affecting the Wi-Fi functionality. To boot into Safe Mode, follow these
steps:
- Shut down your iMac.
- Turn on your iMac and immediately press and hold the Shift key.
- Release the Shift key when you see the Apple logo.
- Once in Safe Mode, check if the Wi-Fi connection is stable. If it
works fine, it suggests that a third-party software or extension might
be causing the issue.

2. Create a new network location: Sometimes, creating a new network
location can help resolve network-related problems. Follow these steps:
- Go to System Preferences on your iMac.
- Click on Network.
- Click on the lock icon at the bottom-left corner and enter your
administrator password.
- Select Wi-Fi from the left sidebar.
- Click on the "Location" drop-down menu and select "Edit Locations."
- Click on the "+" button to create a new location, give it a name,
and click on "Done."
- Select the newly created location from the drop-down menu and
configure your Wi-Fi settings again.

3. Reset the Wi-Fi module: Resetting the Wi-Fi module can sometimes
resolve hardware-related issues. To do this, you can follow these steps:
- Shut down your iMac.
- Unplug the power cord from your router and modem.
- Wait for a few minutes, then plug them back in and wait for them
to fully restart.
- Turn on your iMac and check if the Wi-Fi connection is working.

4. Contact Apple Support: If none of the above steps resolve the issue,
it's possible that there might be a hardware problem with your iMac's
Wi-Fi module. In such cases, it's recommended to contact Apple Support
or take your iMac to an authorized service provider for further
assistance and possible repairs.

It's worth noting that the intermittent behavior you described, with
known Wi-Fi access points appearing and disappearing, does suggest a
potential hardware issue. Professional diagnosis and repair may be
necessary to resolve the problem effectively.

HTH

--
Good luck! :-D
David

On 26/06/2023 08:10, David Brooks wrote:
> On 26/06/2023 02:07, Alan Browne wrote:
>> Yesterday my Wi-Fi on this iMac went off.
>>
>> No way to connect it to my router.
>>
>> I could see other (familiar) neighbor's routers.
>>
>> Fired up iStumbler - usually I'd see a dozen or more local WiFi's over
>> 2 bands.  Now only seeing a few at a time.
>>
>> Did all the usual stuff.  The names of the routers would change from
>> time to time.
>>
>> Occasionally it would connect to one of my 4 WiFi spots (2 private + 2
>> guest).  No internet traffic.
>>
>> Reviewed and reset everything.
>>
>> Removed and restored the WiFi from Preferences.
>>
>> "Make Service Inactive" - reboot - "Make Service Active".
>>
>> SMC reset
>> PRAM reset
>>
>> Briefly today, one of the guest WiFi's worked for about 10 minutes
>> before dropping out again.
>>
>> <sigh>
>>
>> Took the iMac screen off (this is the slim edge edition - I never
>> re-sealed it after a disk change, so just removed the packing tape
>> that was holding the screen on....)
>> Disconnected and removed the display.
>> Disconnected the RF connectors, examined them - fine, restored.
>>
>> Unscrewed the antennas from the edges, examined, cleaned (in case of
>> metal particles).
>>
>> Noted that the grounding "fingers" that bond <cough> the backshell to
>> the display assembly around the main electronics could potentially
>> touch the antennas.  Put Kapton tape in between to make sure there
>> would be no contact when the display "pressed" these in again.
>>
>> Re-assembled.
>>
>> Still no Wi-Fi other than a brief burst of 2 or 3 minutes on a guest
>> access.
>>
>> Deleted a pile of related files in
>> /Library/Preferences/SystemConfiguration/ (per a guide online) and
>> re-booted.
>>
>> The behaviour smacks to me of failing WiFi hardware - the
>> intermittency of known WiFi access points appearing and disappearing.
>>
>> At first thought the antennas or cables - but they are fine as far as
>> I can see.
>>
>> No bluetooth issues - but not sure if it's the same chip.  From the
>> h/w config I don't believe so. (Both are Broadcom).
>>
>> Any ideas appreciated.
>>
>> I'll try a Safe Mode boot tomorrow evening.
>
> Hello Alan
>
> It seems like you have already performed several troubleshooting steps
> to resolve the Wi-Fi issue on your iMac. If the problem persists, here
> are a few additional suggestions you can try:
>
> 1. Safe Mode: As you mentioned, booting your iMac into Safe Mode is a
> good idea. It helps to isolate software conflicts that might be
> affecting the Wi-Fi functionality. To boot into Safe Mode, follow these
> steps:
>    - Shut down your iMac.
>    - Turn on your iMac and immediately press and hold the Shift key.
>    - Release the Shift key when you see the Apple logo.
>    - Once in Safe Mode, check if the Wi-Fi connection is stable. If it
> works fine, it suggests that a third-party software or extension might
> be causing the issue.
>
> 2. Create a new network location: Sometimes, creating a new network
> location can help resolve network-related problems. Follow these steps:
>    - Go to System Preferences on your iMac.
>    - Click on Network.
>    - Click on the lock icon at the bottom-left corner and enter your
> administrator password.
>    - Select Wi-Fi from the left sidebar.
>    - Click on the "Location" drop-down menu and select "Edit Locations."
>    - Click on the "+" button to create a new location, give it a name,
> and click on "Done."
>    - Select the newly created location from the drop-down menu and
> configure your Wi-Fi settings again.
>
> 3. Reset the Wi-Fi module: Resetting the Wi-Fi module can sometimes
> resolve hardware-related issues. To do this, you can follow these steps:
>    - Shut down your iMac.
>    - Unplug the power cord from your router and modem.
>    - Wait for a few minutes, then plug them back in and wait for them
> to fully restart.
>    - Turn on your iMac and check if the Wi-Fi connection is working.
>
> 4. Contact Apple Support: If none of the above steps resolve the issue,
> it's possible that there might be a hardware problem with your iMac's
> Wi-Fi module. In such cases, it's recommended to contact Apple Support
> or take your iMac to an authorized service provider for further
> assistance and possible repairs.
>
> It's worth noting that the intermittent behavior you described, with
> known Wi-Fi access points appearing and disappearing, does suggest a
> potential hardware issue. Professional diagnosis and repair may be
> necessary to resolve the problem effectively.
>
> HTH

I'll come clean! ;-)

My response was the answer provided by AI, unaltered by me!

Quite amazing - to me anyway!

--
David

On 2023-06-25 21:07, Alan Browne wrote:

Well 5 GHz side is working well - I'll keep that going for the day w/o
Ethernet. Has been stable for 2 or 3 hours.

Maybe by dint of trying different things putting in "bad" TCP/IP
settings and the back, etc. has finally written the right settings into
the modem... no telling.

2.4 GHz won't connect.

--
“If you torture the data long enough, it will confess to anything."
-Ronald Coase

On 2023-06-25 21:07, Alan Browne wrote:

- all dead again - the 5GHz side worked for a day - won't come back now.
- I'm guessing the modem has failed in some minor way making it flaky.

I might take it apart again and pull the main board to see if there
might be contaminant on the back of the main board where I believer the
modem is located - this is a "deeper" dive than the prior one - a lot of
screws and connectors, some of them tough to pull out.

--
“If you torture the data long enough, it will confess to anything."
-Ronald Coase

On 2023-06-28 16:39, Alan Browne wrote:
> On 2023-06-25 21:07, Alan Browne wrote:
>
>
> - all dead again - the 5GHz side worked for a day - won't come back now.
> - I'm guessing the modem has failed in some minor way making it flaky.
>
> I might take it apart again and pull the main board to see if there
> might be contaminant on the back of the main board where I believer the
> modem is located - this is a "deeper" dive than the prior one - a lot of
> screws and connectors, some of them tough to pull out.

And now the 5 GHz works fine....

<sigh>

--
“If you torture the data long enough, it will confess to anything."
-Ronald Coase

On 2023-06-28 15:00, Alan Browne wrote:
> On 2023-06-28 16:39, Alan Browne wrote:
>> On 2023-06-25 21:07, Alan Browne wrote:
>>
>>
>> - all dead again - the 5GHz side worked for a day - won't come back now.
>> - I'm guessing the modem has failed in some minor way making it flaky.
>>
>> I might take it apart again and pull the main board to see if there
>> might be contaminant on the back of the main board where I believer
>> the modem is located - this is a "deeper" dive than the prior one - a
>> lot of screws and connectors, some of them tough to pull out.
>
> And now the 5 GHz works fine....
>
> <sigh>
>

Could it be heat related?

When I see intermittent failure of components like that, I think about heat.

See if you can force feed it cool air with a fan.

On 2023-06-28 21:03, Alan wrote:
> On 2023-06-28 15:00, Alan Browne wrote:
>> On 2023-06-28 16:39, Alan Browne wrote:
>>> On 2023-06-25 21:07, Alan Browne wrote:
>>>
>>>
>>> - all dead again - the 5GHz side worked for a day - won't come back now.
>>> - I'm guessing the modem has failed in some minor way making it flaky.
>>>
>>> I might take it apart again and pull the main board to see if there
>>> might be contaminant on the back of the main board where I believer
>>> the modem is located - this is a "deeper" dive than the prior one - a
>>> lot of screws and connectors, some of them tough to pull out.
>>
>> And now the 5 GHz works fine....
>>
>> <sigh>
>>
>
> Could it be heat related?

Always possible. I have iStat Menus and there is nothing temperature
intense going on in there - though there's no sensor on that chip, itself.
Most things are in the 44 - 60°C range (under light use) - fan is at
lowest speed (1200).

>
> When I see intermittent failure of components like that, I think about
> heat.
>
> See if you can force feed it cool air with a fan.

While I was in there I did some cleaning up (dust). Not practical to
operate the computer while it is open.

So - yesterday the 5 GHz quit again (after the computer "slept" for a
while) and now it is working again.

2.4 GHz doesn't work. Well, it will show as on, has an IP address, but
won't actually move data.

Not sure I want to spend much time on this either - the iMac will be 2nd
stringer soon - hopefully this autumn.

Don't "need" the WiFi, but nice to have everything working.

--
“If you torture the data long enough, it will confess to anything."
-Ronald Coase

On Thursday, 29 June 2023 09:20 -0400,
in article <KyfnM.3$8Ma1.1@fx37.iad>,
Alan Browne <bitbucket@blackhole.com> wrote:

> 2.4 GHz doesn't work. Well, it will show as on, has an IP address,
> but won't actually move data.

Is the IP address self-assigned, ie. within 169.254.0.0/16? These are
not routable addresses.

$ whois -h whois.iana.org 169.254.0.0/16
% IANA WHOIS server
% for more information on IANA, visit http://www.iana.org
% This query returned 1 object

inetnum: 169.254.0.0 - 169.254.255.255
organisation: IANA
status: assigned

remarks: http://www.iana.org/go/rfc3927

changed: 2005-05
source: IANA

--
David Ritz <dritz@mindspring.com>
Be kind to animals; kiss a shark.

On 2023-06-29 15:06, David Ritz wrote:
> On Thursday, 29 June 2023 09:20 -0400,
> in article <KyfnM.3$8Ma1.1@fx37.iad>,
> Alan Browne <bitbucket@blackhole.com> wrote:
>
>> 2.4 GHz doesn't work. Well, it will show as on, has an IP address,
>> but won't actually move data.
>
> Is the IP address self-assigned, ie. within 169.254.0.0/16? These are
> not routable addresses.

10.117.0.0 ( I believe that's /16 ).

So 10.117.0.2 ... 10.117.255.254

Manually set IP on the Mac WiFi as I try to get it going
10.117.77.241

Mask: 255.255.0.0

As they've been for 10+ years.

As I write this I'm on the 5 GHz band and it's holding well. (Will
probably die again).

Let's try 2.4 ...

No joy ...

But 5 GHz came back, there's that...

--
“If you torture the data long enough, it will confess to anything."
-Ronald Coase