I was sure I played my last turn. I surely forgot to press 'e' and choose 'Save game and quit'.
As I am travelling for my work, I am not connected 24/7 (but I am still able to play at least twice a day) so I did not double-check that my turn was sent.
I'm going to have to take the server down for an hour or two pretty soon, as I have to physically move the machine. I'll put it back up with 24 hours to host.
edit: it's back up now, everything should work fine