iOS WG Battery Life

[kolargol]

> Possibly, is PersistentKeepalive defined at the "server" endpoint for your iOS peer ?
>
> I would expect a measurable additional battery usage if either peer endpoint had PersistentKeepalive defined (non-zero).

Both server and peer have PersistentKeepalive disabled, there is no fancy apps runnign in backgroud - and i am using exac same WiFi and VPN endpoint (for OpenVPN and WG comparision).
WiFI connection is stable and have strong signal, same with LTE.
The battery grap shows sharp down in the night as something continuesly draing battery (here wg)
How can i debug it ?