I think I got up to 300 or so days on my old Athlon XP Gentoo server. I have “upgraded” since then and my current server can’t go more than 2 days. I have an arduino connected to the motherboards reset button pin that resets it whenever the bash script that communicates with the arduino stops running but even that somehow still crashes at least once a week and needs manual intervention.
Been using Linux since the 00s. Took until maybe 2014 or 2015 until it got to the point where I no longer had Windows even on dual boot.