Sporadic connection to devices on LAN since upgrading to Sonoma

I was running 12.3 just fine on my home network, but decided to finally upgrade to 14.1. Since the upgrade, I can't reliably connect to any devices on my network. WAN access is totally fine. I can occasionally connect, but it will disconnect on it's own anywhere from 1-10 minutes later. The problem is the same whether on wifi or ethernet. I don't see any network or connection errors in the Console when the disconnects happen.

For example, I've tried connecting to my Synology NAS via the web browser, SMB, AFP, WebDAV and SSH. They all sometimes work, but never consistently. As in, sometimes I get an immediate "can't connect" error, and sometimes it will connect but then disconnect within a few minutes.

The reverse is also true. If I try to connect from my PC to the Mac, it fails. I have File Sharing enabled and access via smb.

All other devices on the network connect to each other with no issue, and I wasn't having any issues before the upgrade. So, it has to be something with the Mac itself. Because it's not consistent, I can't attribute it to a hosts file, or dns cache (which i've flushed) or anything else that I could think of as a permanent issue. It also isn't protocol specific, where I could just blame SMB or a port.

Anyone else experienced this issue?