Run server with 1.24 (vanilla, Perf, Perf2, perf3 or perf4 - we had it with vanilla and perf4)
Install package as provided (see rar-file)
==> Server runs fine with 60 players (20-ish ServerFPS, 7-12 CPS), 0 Desync issues
Update to 1.26 via SteamCMD
==> Players >= 30 - desyncs are noticeable
==> Players >= 40 - desyncs are the regular norm
==> Players >= 60 - desyncs are so massive that your vehicles start flying and your having a discrepancy of 5+ seconds between action and reaction on screen.