Hello, I am back with news.
Thanks @cslorabox and @arjanvanb for your comments and feedback.
I do a complete analysis of the data and I think I’m better understanding the picture.
First of all i am based on Chile, LATAM, here we use the AU915 Frecuency Plan. (Latam is messy and different countries use different regulations so AU915 fits in most countries)
I have distributed the 16 sensor in 4 points (4 sensors per point), and I’m getting data only from point 1 and point 2, even more so, points 3 and 4 are the furthest. this is already giving me some clue.
In this image i can see that there are messages with SF9 and messages with SF12 (all masagges has the same payload size). I review each packet and noticed that all packets with SF12 takes 1482.8 ms and that exceeds the allowed limit for AU915 according to this tool: [https://avbentem.github.io/airtime-calculator/ttn/au915/11] all those packets are the ones I don’t get in my DB(and i dont see in the TTN console either)
So my question now is: How can I make the devices transmit at a SF that does not exceed the limits? do i need to improving the antennas and the points where the devices are located? another idea?
(I can understand the hole thing reading this post: Limitations: data rate, packet size, 30 seconds uplink and 10 messages downlink per day Fair Access Policy [guidelines])