That's been my experience as well.
My workaround for part of that is using many SSIDs.
A. The SSID that covers both bands, in all areas
B. Two more SSIDs, one for each band -- again, used in all areas
C. Another SSID just for the AP in the garage (which also has A and B SSIDs)
It has some advantages: I like being able to set a portable device to SSID A. These things usually figure it out well-enough while moving around. When someone visits and asks for wifi access, I give them SSID A. It works; it's just not always perfectly ideal.
It also prevents fixed devices in the garage from deciding to use APs in the house; it never works well for them when that happens. (The opposite problem hasn't been observed to be an issue yet.)
And it lets me decide whether any device is able to use 2.4 or 5GHz, in the usual way of having per-band SSIDs. If my TV streamer weren't plugged in with ethernet, then I'd set it to use the 5GHz-only SSID.
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A big downside is that it's ugly. Another is that the per-device config is spread out amongst all of the devices instead of centralized, but that's not so bad: I just make the SSID decision at initial device setup and forget about it.
This also impacts maximum throughout / performance. You want to try at limit to 4 BSSIDs per AP, tops.
I'm at 4.
What are the nuts-and-bolts reasons that would make 5 perform worse?
Each take about 10msec airtime (beacon+various broadcasts+probe responses+acks etc NOT including actual client data). (simplified)
Beacons repeat every 100msec. So you're already wasting up to 40/100 of airtime for management/misc frames
Wifi is a shared half duplex medium
Thanks!
Previously, I've never thought much about the airtime required for beacon transmission, nor that it increases as SSIDs are added.
Thinking about it now, I can see some ways to improve the cost of these SSIDs.
Like, increasing the minimum speed/excise old protocols (I probably don't need 1Mbps 802.11b at all in 2026 and can't think of any strictly 802.11b-only device that I've ever owned) to decrease the time that beacons use.
That seems like one obvious improvement that should be is free of other tradeoffs.
There's a few other things I can think of, but I'm not done thinking about it yet. :)