This is not at all fixed for me either, and I'm frankly pretty baffled that this issue is still unresolved. I assume it just dropped off Sony's radar after they put the "solved" tag on it, without making sure if people actually stopped having the problem.
At this moment, the connection is terrible for me. I have the phone right next to me, which is about 5m from the Wi-Fi hotspot. When the screen turns off, it takes WhatsApp Web about 5-10 seconds to report that the phone is not connected anymore. As soon as I turn the screen back on – I don't even have to unlock the phone – the phone immediately connects to the Wi-Fi again, and WhatsApp works again within 3 seconds. I've done this about 40 times in the past half hour and it was 100% the same every time. Screen off, Wi-Fi drops, screen on, Wi-Fi reconnects. I have this on two different hot-spots, on both 2.4GHz and 5GHz band, dynamic or static IP, and regardless of signal strength.
The legacy DHCP client sounded promising, but didn't change anything for me.
I have an unlimited data plan now, so the phone switching back to 4G constantly is at least no longer a financial issue for me, but that can't seriously be the solution, to just accept that Wi-Fi isn't working.
Sony, what are we supposed to do?
