Connection to server times out

[Ackapus]

Running DW20's latest pack, v1.13.2

Server sits in the same room. Got two other players on the server, one is in the same room with me and connects locally, other lives on the other side of town and has a worse computer than mine.

I've cut the view distance down to 8 and added -Dfml.readTimeout=120 to the server start.bat file's java.exe arguments and to my own modpack instance Java runtime arguments. Both server and my client are set to 8GB max memory. I also shut down my antivirus while running the game. However, the timeout happens in about 35-40 seconds regardless of the readTimeout value I have (first tried it at 60, then 90).  Also, the server console starts processing things for other players joining the server well before my client gets timed out, and never processes anything for my client beyond the initial handshake.  Local client just gives the connection closed by host error, or says it failed to connect. Server console says it's disconnecting me (gives identity value for my profile and skin): Took too long to log in.  That's it, nothing else.

I've even put the Java console for my local game on high priority in Task Manager and installed the same version of Java on the server as on my client.

Opened up the port for the server on my computer, inbound and outbound.  Running no antivirus on the computer.

What else can I do?