Why can't I join a LAN world?

I'm trying to connect to my sister's LAN world, and I get the error message Failed to connect to the server Connection timed out: no further information. I'm using an OMEN Laptop and the Java Edition of the game. I've tried the following:

Disabling VPN and Proxy,

Using Direct Connection instead of just connecting regularly, and

Checking if we were friends on the Xbox game bar (and we are).

None of these common troubleshooting suggestions seemed to have worked, and I'm starting to get desperate.

Please help.

:)