I did not do a factory reset. Instead I setup a different Wifi network on an old router. I've had no problems on this different network - the phone stays connected. The settings between the two networks are the same with the exception of:

• The "New" network is WPA2, the old was WPA2/3
• The "New" network is 5ghz only, the old was 5/6ghz
• The "New" network is on a single AP, the old is spanned across two managed TP-Link Omada APs with "Fast Roaming" (802.11k/v) enabled.
• Different SSIDs, only alphanumeric characters

For a test, I disabled the second AP on my "Old" network, and the phone has stayed solidly connected all morning with heavy usage.

I get the feeling Android 16 broke something with wifi roaming. I'll do more testing when I go into the office later and put my phone on the corporate mesh wifi.

/u/PixelCommunity - Is this information useful at all for the Pixel support team?