Dedicated Server: Invalid Tenant ID

I looked at some of the other "Invalid Tenant ID" posts before posting. I have a class of 30+. During a class, as everybody is logging into the dedicated server, a certain percentage of the class will receive this error. They will receive it repeatedly, until finally it lets them in. The server is running 1.21.133.2 and all clients are on 1.21.133. The server has 32GB/RAM and plenty of CPU power.

This seems to happen no matter what world I'm running at the time. We use multiple worlds throughout the class, but using the same server.

Are there any server-side settings I could alter to help with this issue?