Go into Sound settings, find your Realtek device, and disable it there if you don’t want it to play anything at all.

@D0llyy, yes there are many tools for many OS's that can send the magic packet to wake up another computer. Windows: https://www.nirsoft.net/utils/wake_on_lan.html Mac: https://formulae.brew.sh/formula/wakeonlan Ubuntu: sudo apt-get install wakeonlan