[altfredd]

Note that TCP Keep-Alive might not play well with mobile devices.

Mobile operating systems can use application-level keep-alive packets, because those can be easily attributed to individual applications: an applications receives a TCP/UDP packet during low-power CPU sleep mode, asks system to wake up (by e.g. taking a wake-lock), and the system takes note who caused the wake-up. TCP Keep-Alive happens below application level, so it may be disabled, even when application can still be reached.