The WiFi on my BV9600 Pro is unusable. Even sitting right beside my WiFi access point, it switches between 2.4GHz and 5GHz for a while and then completely disconnects at random. The error message displayed in debug mode is NETWORK_SELECTION_TEMPORARY_DISABLED and NETWORK_SELECTION_DISABLED_ASSOCIATION_REJECTION.

I've finally figured out why my BV9600 Pro keeps switching to the SSID on the 5GHz band even though the signal is almost out of range, rather than sticking to the same SSID on the 2.4Ghz band with a much stronger signal.  It's because all the 2.4GHz SSIDs keep disappearing.  I ran a WiFi analyzer app and the graph of the 5GHz SSIDs stays relatively flat across time.  The 2.4GHz bands keep turning on and off every 10 or 20 seconds.  The graph of 2.4GHz SSIDs stays flat for a while, dips to nothing, and then turns back on. No wonder the phone wants to stick with the 5GHz SSID, no matter how faint it is; at least it doesn't flip on and off.

Now, since no-one else has reported this, I can only assume that I have a phone with a faulty radio in it.  How do I go about getting the phone replaced under warranty?

I've managed to sort out the Wi-Fi problems somewhat by figuring out how to give my mesh router separate 2.4GHz and 5GHz SSID names. The phone really wants to hold on to that 5GHz SSID though, even when it's almost out of range and there are strong 2.4GHz saved SSID's near.

Thanks for the tip, I also have to fight with the unstable wifi. It bounces back and forth between 2.4 Ghz and 5Ghz, before it can no longer connect to the Wi-Fi at some point. I always have to go into flight mode and back.

Have now forced the phone in the 2.4 Ghz frequency by changing the SSID and now it remains stable.