I guess (power) users were triggered by two (main) things: 
- Connect HA via Wi-Fi
(red flag for servers) - Buying (not having!) a raspberry pi to use as HA host
(very bad value for money)
They use different SSIDs. Can’t say I tried turning off the 2,4GHz WiFi though, don’t see how that would help.
And in response to @Arh, it’s not an attenuation issue. My cellphone and my PC are getting excellent (full) signal strength right next to the current PI 3B+, it just won’t scan for any 5GHz networks though the companion app (and like I’ve said, I’ve tried adding the region code to the network/my-network file). It failed to connect to the 5GHz (the router wasn’t assigning it any ip or seeing it) and I had to re-do the network/my-network with 2.4 GHz settings.
Not really. It’s cheap and easier, but the performance sucks. The green is entry level hardware that comes pre-configured. The Yellow is discontinued. Spend the extra $20 and get a NUC form factor X86 based machine as your next, IMO.
And if you like PI’s, you might also have your 2.4 and 5 on the same SSID, meaning the router picks the band that the device can handle. That PI might work best on 2.4 because it’s too slow for anything else.
If you are using the same SSID for both bands, it will cause problems with IOT devices, so watch that also.
I’ll get the PI5 for the hell of it because I really want one. I really do appreciate the advice though. If the PI6 doesn’t step up their game significantly though, my next upgrade will be a MiniPC for HA.
Btw, @francisp Would it be too much of a trouble for you to post your network/my-network file? Maybe I did something wrong…
@finallen poke
I’m really eager to see if your config is any different than the standard one that usually comes up in searches, ie:
[connection]
id=hassos-network
uuid=72111c67-4a5d-4d5c-925e-f8ee26efb3c3
type=802-11-wireless[802-11-wireless]
mode=infrastructure
ssid=(my router’s SSID)
#Uncomment below if your SSID is not broadcasted
#hidden=true[802-11-wireless-security]
auth-alg=open
key-mgmt=wpa-psk
psk=(my router’s password)[ipv4]
method=auto[ipv6]
addr-gen-mode=stable-privacy
method=auto
I just tried it again on my 3B+ using a CONFIG labeled usb stick (waay easier than taking the case apart each time to get the SD card out which is what I used to do the last time around lol), just replaced the ssid with the 5GHz, wlan0 didn’t get an ip in the cli at boot.
Plopped the stick back into my pc, changed the ssid back to the 2.4 GHz, works like a charm. I’m really at a loss here. Just wondering if there’s a special setting I’m missing to get it running on 5GHz. Maybe it just doesn’t work with the 3B+ for whatever reason 
Good news is I’ve ordered my PI5 this morning in the hopes it will reach the local store by Saturday. I’d like to have the weekend to myself and migrate everything in piece. As for the 5GHz, hopefully it “just works” on the PI5. If it doesn’t ima kill myself lol.
Yes, but it only sees 2.4GHz networks.
That’s kinda why I’m thinking I’m missing something in the original config file (I tried various AI responses to adding a country code but to no avail).
Well I got my Pi5 the other day 
Cute little piece of hardware. And yes, the 5GHz WiFi works, so ty once again to the two people who reported it worked on the Pi4 and 5. I’m guessing since the 3B and 3B+ use the same image, it’s disabled in the software bc “reasons”. The 3B+ has 5GHz support while the older 3B does not.
But anyway, just wanted to report that even though the WiFi works fine, I still get the following error once or twice in the CLI just before or seconds after the supervisor starts:
ieee80211 phy0: brcmf_p2p_send_action_frame: Unknown frame: category 0x5, action 0x1
Seemingly only on the 5GHz band, although I will admit I didn’t do any exhaustive testing. It doesn’t seem to affect anything, but it’s still annoying and irks me somewhat that these things still haven’t been ironed out. It’s been out for what, two years now?
I tried googling, someone on libreelec forums reported the exact same error and apparently it’s to do with outdated drivers. Would be nice to get an update on that front as well.