About RAK831-Pi3 & RAK811-Wisnode Airtime

Hello.

I have a question.

I am testing with RAK831-Raspberry-GW and RAK811-Wisnode.

Using “The Thing Network - Console”, “RealTerm”.

and My RealTerm Console is :
at+mode=0
Mode switch OK!Reset now…
Welcome to RAK811.
Selected LoraWAN 1.0.2 Region: EU868
Initialization OK!
at+join=otaa
OK
at+recv=3,0,0
at+send=0,2,000000000000007F0000000000000000
OK
at+recv=2,0,0

Question :

My equipment works normally. But the communication speed is too slow.

How can I change the SF value from 12 to 7?

Thank you.

test