Out of curiosity: do you have more than 9 devices on the border(s) between router and node(s)?
It sounds like a lot of devices that are suffering from roaming. But, by the settings, it should roam not faster than every 5 minutes, so a decent quality device should not suffer at all.
I only have one Google Mini that decides to roam every now and then. Few times per day, but it's always working as expected.
I am not convinced that Roaming Assistant works as well in 386 as it did in 384. I have tried different RSSI threshold triggers and don't see the system move clients as efficiently as in 384. Binding in 386 is a way to get clients to the appropriate node quickly.
In my environment I have about 30 wireless devices online at any given time. A number of my devices are IoT things that don't physically move and are sensitive to bandwidth requirements and switching nodes, like wireless security cameras and wireless audio speakers to play music in rooms. I also have a number of appliances and smart home devices, like lights, thermostats, etc. that never move. I have deduced that many of the devices probably don't have the greatest WiFi driver software because a device will be right next to a node with very strong signal, but decide to hop to a different node with much worse signal. So, many times these devices are on the perimeter of my house and not in between nodes trying to decide between nodes with similar signal.
I have a lot of concrete and steel in my house that blocks signal and ended up with multiple AiMesh nodes. I want to get as many of the devices that physically roam around the house on 5 Ghz as often as possible. I have 3 fixed channel SSIDs (no SmartConnect) in my AiMesh 2.0 environment to deal with my scenarios:
x - 2.4 Ghz AND 5 Ghz for clients that roam heavily and are good at choosing when to move to the best node and frequency - mainly Apple devices and some laptops. Many IoT devices with only 2.4 Ghz radios use this across the mesh network. The majority of devices use this SSID.
y - 5 Ghz guest SSID shared to AiMesh nodes AND allow Intranet for clients that roam heavily, but are bad at picking 5 Ghz over 2.4 Ghz - some laptops and gaming devices that use high bandwidth. This option to share SSID across nodes is new in 386. Originally I set the laptops to only use 5 Ghz radio, but that broke Miracast to share laptop screen to TV.
z - 2.4 Ghz guest SSID with allow Intranet for IoT clients I want to ALWAYS be on the main router. I have some devices that seem to freak out when they see multiple APs with the same SSID, like my thermostats and a WiFi light switch, so I want them to only see and connect to one SSID even if they have weaker signal. If I don't do this they become unresponsive from the apps.
So I use binding to get a bunch of confused devices to the preferred node, plus benefit from resiliancy if that node fails. Right now that's my 9 biggest offenders and it's working well.