LORAWAN_Net_Reserve - How to use this feature on Cubecell HTCC-AB02 #284

Hello
I am building application that measures temperatures. I want to be able to reset the device and just send data, without the need to join the network (I have the uplink mode set to UNCONFIRMED and I use OTAA mode).

The device I use is CubeCell HTCC-AB02 and the server - The Things Network

There is this parameter in Arduino config LORAWAN_Net_Reserve and in description there is:

/* set LORAWAN_Net_Reserve ON, the node could save the network info to flash, when node reset not need to join again */
bool keepNet = LORAWAN_NET_RESERVE;

Do you have any example where this feature is used? I looked and cannot find anything about it.

When I set LORAWAN_Net_Reserve to ON in Arduino IDE I am getting this error:

00:59:06.953 -> Wait 3s for user key to rejoin network
00:59:06.953 -> LoRaWAN EU868 Class A start!
00:59:07.186 -> User key not detected,Use reserved Net
00:59:07.219 -> Next packet send 26561 ms later(random time from 0 to APP_TX_DUTY)

(I am not using user Button at all)

Should I disable Frame Counter on server side using CLI? (if yes please help me how to do it - this is what i researched but I have no idea how to do it)

I will be grateful for any help.
Regards,
Luke