ESP-NOW Speed transmission

[flavietto]

Dear everyone,
i'm working on a network projectt using esp-now library on esp12.

I've encountered many problems but at the moment i'm able to send-receive packet from a node to another.
But i obtain poor network speed. Every time i use esp_now_send function i obtain from 1 to 200 fail result before packet is received from other node.

Can someone help me?
On user guid i found on note that "handshake" is a prerequisite for good comunication but there is no other mentions about handshake in ESP-NOW documents.

Thanks you all.
Flavio