Okay, after like an hour or two of Googling I'm totally frustrated and nearing giving up.

I've tried every possible troubleshooting method I've found. Delete/rename Documents folder for BYOND, install latest version, install 2022 version, whitelist both BYOND and Dreamseeker in Windows Firewall, VPN on, VPN off, VPN to several different servers, restart, restart again... and so on.

What the hell is going on???