I'm thinking theres something going on where DHCP lease renewal packets are causing timeouts with 14.
I am absolutely 100% convinced that a god chunk of 90002 errors are being caused by the packet loss caused during these lease renewals.

I can replicate these errors every single time I test it.

I can only assume that following the server splits, something changed and the servers are now significantly more sensitive to these losses.
This right here. My VPN tracks my packet loss, and if it makes it to 1%, I get kicked. Sometimes it takes even less than that for the game to kick me.