Indoor Wi-Fi Roaming with OpenWRT

Summary

A few months after writing up the Cudy AX3000 units and moving the house over to OpenWRT, I ended up revisiting the one bit I had deliberately waved away as “good enough”: roaming. A real house, with a mix of phones, tablets, laptops and a few stubborn IoT things that insist on staying in 2016, has… issues. But they’re not always obvious, and given we’d both upgraded the 5GHz band and changed the locations of the access points, it took a while to figure out where the new rough spots were. If you’re just tuning in, I have a hard split between a legacy 2.4GHz network and the modern 5GHz one. I already had client-managed roaming and basic handoff guidance, but now I added usteer, 802.11k neighbour reports (because hostapd was not cooperating), and things are now pretty much perfect. The long version is below, with anonymised data and enough detail for future me to remember why I did this. Why I Did Not Merge The SSIDsThe obvious advice for roaming is “use one SSID everywhere”, and that is often correct if you’re running Wi-Fi in an office, a public venue, or generally somewhere where you don’t have (or care about) legacy devices. It is also not what I did, because the 2.4GHz side needs to remain friendly to older and slightly terrible IoT devices, which means WPA2 compatibility and a conservative setup. The 5GHz side is where the more modern clients live, and despite losing 5GHz access for a couple of things, I was happy to move it to WPA3. So this is what things look like from a high level: 2.4GHz: legacy-compatible WPA2-ish network for IoT and old clients. 5GHz: modern client network with WPA3/SAE 2.5GbE backhaul across four “dumb” APs Zero cloud management or vendor-specific software. Nada. Zilch. Non-negotiable. User FeedbackHowever, I got a few complaints that when moving about the house, iPhones, iPads and MacBooks would not switch to another AP. Since our flat is wrapped around a couple of elevator shafts and there are a few spots (like the kitchen) where tiling...