Server always crashes when autosaving on day 4

My 5 friends and I have recently started playing DST, with me hosting the server. Our first world was running perfectly at first, but when saving at the end of day 40, it randomly crashed, not saving the progress made during the day. We tried again and again but whatever we did it always crashed.

I tried disabling mods, changing the settings, converting to local/cloud save, duplicating it, but with no luck. So I tried a new world, which always crashed when saving at the end of day 4. So my friend tried hosting the server, but we had the same problem - saving on day 4, and the game crashes.

I then decided i will try to run a dedicated server from my pc, to see if the steam servers are causing this. After 5 hours of setting it up we tried it out and ...... it crashed again, when saving on day 4.

It's not the steam servers, it's not my computer, it's not any mods. Right now I am out of ideas how to fix this, I haven't found any posts about the same problem, so I am very lost as to what is happening.