Mobile clients frequently become unreachable even with TLS connection (which is in fact TCP) when the app is in background.
I'm closely monitoring a few mobile clients on our local network. Since they reside on our local network, I discovered that some clients wake up right after they receive an icmp echo request. I wrote a script that pings local clients every 20 seconds so I can effectively keep them alive all the time.
This hack works for the following devices.
Samsung Galaxcy S5 (Android 4.4.2)
Samsung Galaxy A7 (Android 4.4.2)
But not for
Samsung Galaxy S6 (Android 5.1)
The "keep alive wifi" and "stay awake" options don't help.
This is the most annoying issue I found with almost every softphone app.
Is there a generic solution to fix the issue for all devices and non-local clients?