System info, if it's needed:
OS: Linux Mint 22.3 x86_64
Kernel: 6.8.0-90-generic
My computer was connected to the same network as my Xteink X4, and on the X4 it looked like the connection was established succesfully. I dual-boot Windows 10 on the same PC, and there I could connect without problems and transfer books through Calibre.