BT (classic) Modem Sleep

[azathoth]

Hi,
I'm trying to use BT modem sleep mode with no success.

Relevant configs:
Bluetooth controller mode (BR/EDR/BLE/DUALMODE) (BR/EDR Only)
Bluetooth Modem sleep mode (ORIG Mode(sleep with low power clock))
Bluetooth low power clock (Main crystal)

My device has to behave like an SPP SERVER so I'm using esp-idf/examples/bluetooth/bt_spp_acceptor as test bed

I need to keep the connection while going to sleep and wakeup when the client sends data.
I can't find any suitable doc.
Nothing expected works.
I'm in desperate need for help.