Wi-Fi stops working on /some/ Raspberry pi cards

I recently had an RPi where the Wi-Fi wouldn't connect after a
power-down reboot. No settings were changed, and I could see DHCP
requests going out. Didn't have the time to resolve it, so used
Ethernet instead as a connection was to hand. Other RPi cards on the
same network have rebooted with power-down multiple times without problems.
However, I've just had a second RPi with the same problem (and same
solution). No configuration change, but no Wi-Fi connection. These RPi
are both model 1B.
One other change has been adding a second access point (2 GHz) with the
same SSID. I've read that this is OK and the device will simply pick
the strongest signal and connect to it. Certainly the 5 GHz devices
such an a iPad, RapPi-4B and Pixel 3 phone. don't seem to be affected
(different SSID). I'm using a separate router connected to my wired
LAN, and the two access points are connected to that LAN. No combined
ISP modem/router/Wi-Fi box involved
Does this ring a bell with anyone?
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Cheers, 
David 
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David Taylor
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I found I needed to split SSIDS and tell the pi exactly which one was preferred.
Cant remember which file it was specified in tho
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Reply to
The Natural Philosopher
Should be /etc/wpa_supplicant/wpa_supplicant.conf, right? Which I remembered as having 600 permissions, which it really should have because it contains wifi passwords, hashed or even clear text, but right now when I checked it was 644! I really can't imagine that that was always the case. Rather disturbing that there was a "secret" update along the way, if it was that.
(Of course, the standard setting of Raspbian is to not require a sudo password anyway...)
Reply to
A. Dumas
mine is stuck at 600
Yup. And the pi tries them *in order* at boot time.
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Reply to
The Natural Philosopher
Can be customised by assigning "priority=" directives where higher = earlier. Although apparently that gets ignored when using "scan_ssid=1" (for that network, or for all, I don't know) which you would use to forcibly scan for a network with hidden SSID, but I don't have that. Also I just reorder the entries instead of using priority.
I always forget, I maybe never quite figured out, how one would manually associate the Pi with a particular network configured in wpa_supplicant.conf from the command line, which I sometimes want when for whatever reason the Pi didn't pick up, or lost, the main network at some point.
Reply to
A. Dumas
The SSIDs are a blind alley IMHO. Multiple AP networks seem to have some mystery about them in the hobbyist community where they're regarded as esoteric, but these things are designed for enterprise deployment - AP selection and indeed handover were baked into the spec on day one and essentially work automatically. I'd look a bit deeper into the network configuration.
How are the two routers connected? For a single, seamless network you would generally want to connect them LAN port to LAN port with ethernet. With consumer level gear if you want another configuration - e.g the second router as repeater - you're probably best with an actual AP as opposed to a second router since they are generally slightly more flexible in their bridging options.
What does the new router's IP setup look like? I suggest a static IP assignment clear to any DHCP pool but with the same network address and and match. Obviously the IP assigned needs to differ from the first router. Default route should be the first router assuming that is where internet connectivity comes from, but shouldn't be too important since you're essentially using it as a layer 2 device - that is it's knowledge of IP should be basically dormant.
In terms of DHCP the simplest way is simply to disable it on the second router in which case the first will supply addresses to both APs (assuming that it was supplying the addresses in the first instance). A simple form of fault tolerance can be provided by adjusting both routers to supply from non-overlapping pools in the same subnet, e.g. 192.168.0.64/27 for the first and 192.168.0.96/27 for the second, assuming a 192.168.0.0 base address. That way leases are still assigned if either router is powered down or hung. I'd only play with that after the network is working, though.
Finally, just one clarification, can you explicitly confirm the Pi is not getting a lease of any form over DHCP, not that it is getting one that does not provide connectivity?
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Andrew Smallshaw 
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Reply to
Andrew Smallshaw
Except they simply do NOT.
I have three WAPS here. I started out giving them the same SSID/password. My laptop and my mobile phone would both resolutely hold on to the one they initially connected to long past the time when the damned things speed had dropped to unusable.
Now they all have different SSIDs so I can force the devices to use the nearest one ...
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Reply to
The Natural Philosopher
Unless of course you use enterprise grade equipment, when they do.
Yep I had that right up until I ditched the consumer grade APs and installed low-end enterprise grade ones, everything I've tried just roams automatically and sensibly between the two of them even though they are overkill and either alone can give fair coverage in the worst spots. They're also designed for hundreds of parallel connections so the dozen or so devices round here at peak don't phase them at all.
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Steve O'Hara-Smith                          |   Directable Mirror Arrays 
C:\>WIN                                     | A better way to focus the sun 
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Reply to
Ahem A Rivet's Shot
So tell me how do professional garde waps manage to make the clients behave differently?
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Reply to
The Natural Philosopher
They have a central controller that looks at all the APs, and all their clients, if it wants a certain client that is using AP1 to switch to AP2, it will tell AP1 to disassociate it, and to refuse re-association, the client will then try to connect to AP2 ...
Reply to
Andy Burns
Ah. Central controller...
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Reply to
The Natural Philosopher
Would you tell us what these boxes are? I'm just about to replace the house wifi network.
Regards, Stephen
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Reply to
Stephen Pelc
I can't tell you what Rivet's are, but my experience with Unifi saucers has been entirely positive.
Reply to
Roger Bell_West
Them's the ones. Nice name.
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Steve O'Hara-Smith                          |   Directable Mirror Arrays 
C:\>WIN                                     | A better way to focus the sun 
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Reply to
Ahem A Rivet's Shot
========================= Fixed - turned off the 2nd 2G network and the two RPi cards reconnected to Wi-Fi. They were both model 1B running Wheezy, with Wi-Fi adapters purchased around the same time.
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Cheers, 
David 
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Reply to
David Taylor
Out of interest, does it connect if you turn off the first 2.4GHz access point?
Reply to
Andy Burns
Heavy overlap of coverage from each AP? Were they on the same channel? Or channels that multally interfere? Only chs 1,6, & 11 don't in 2.4 GHz.
I run two 2.4 GHz APs on the same channel and same SSIDs without problem but they have minimal coverage overlap. Thick walls...
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Cheers 
Dave.
Reply to
Dave Liquorice
The simple answer is I didn't try that.
Longer: AP1 was the only AP for a long time, and the only 2 GHz those early RPi cards would have known. I bought AP2 as a backup and because I wanted to provide better 5 GHz overall coverage. AP2 was in the more central location, so I left AP2 running on 5 GHz and disabled the 2 GHz on AP1. Some of the cards needed a reboot, or the Wi-Fi USB unplugged and restored. It wasn't all quite as smooth as I have hoped.
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Cheers, 
David 
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Reply to
David Taylor
I hope they were on different channels, but at least AP1 was set to Auto. It would be nice to have known, though!
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Cheers, 
David 
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Reply to
David Taylor

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