I’ve seen this issue come up before, so I’ve upgraded to latest firmware already - v4.3.7. The firmware does seem to improve things a little. Instead of disconnecting almost immediately, the device disconnects after a minute or two and sometimes reconnects automatically. It’s still unworkable though as there’s a minute of downtime every 2-3 minutes, and won’t always reconnect.
At the same time, I have my phone connected seamlessly to the router, as well as a Chromecast that is continuously streaming video during all these Chromebook interruptions. It seems to be a specific compatibility issue with Chromebook.
Device is Asus Chromebook CX1500 aka CX1.