Minecraft – “Waiting for chunk…” or “Loading terrain…” when joining a LAN game

I am trying to play with a friend of mine over Hamachi in her world via the LAN game option. This worked fine until a few days ago. Whenever I try to join her world, one of two things will happen:

1. I can join her world, but no chunks are loaded and the debug menu says "Waiting for chunk" (see image below)

2. Before I join her world, my Minecraft gets stuck on the "Loading terrain…" screen.

Both eventually end with a "Server timed out" error. She played in the same way (over Hamachi, LAN game) with another friend (or me a week ago) without any issue and can join a world running on my computer without any issues. My computer is a potato though, which is why she would like to be the host.

I am currently running on Linux, she is on Windows, so I thought this maybe was a "Linux being weird" type issue, so I slapped a fresh Windows 10 installation on my computer, downloaded my graphics card drivers, Hamachi and Minecraft, only to be greeted with the same behavior I described previously.

We both added exceptions for Minecraft/Java to our firewall, disabled any anti virus software, tried playing on a different world, [F3]+[A] to reload chunks and restarted our computers and routers. The fact that her friend could join her without any issue makes me think that the issue is definitely on my side, although I can join big servers, like HiveMC, without any issue.

After hours of googling and trying solutions, I am totally lost. The last difference we could think of was that I have a Mojang account without any connections to Microsoft, and she and her friend have an account tied to Microsoft. But I cannot force my account to migrate and have to wait for Microsoft to unlock this option, which is why I cannot test this.