CRC mismatch despite having identical configurations for Client and Server

I'm trying to write my own network manager with separate client and server gameobjects, but connecting with a client to the server results in "UNet Client Disconnect Error: CRCMismatch", despite the client and server configuration being the same.

Configuring the NetworkServer on the client fixed this when running inside the editor, but not in the build. Also, it's odd why would I need to do that on a client.

Here's the code for...

CRC mismatch despite having identical configurations for Client and Server