Packets lost streaming data from multiple boards
I'm testing streaming data from four MetamotionR boards
_ Hardware revision [0.4]
_ Firmware revision [1.5.0]
_ Model number 
with the integrated bluetooth of a RaspberryPI 3 model B+. On the raspberry pi was flashed the image received from Mbientlab by email (https://mbientlab.com/tutorials/MetaHub.html#download-image). The python code is attached.
I'd like to stream simultaneously accelerometer (25Hz), gyroscope (25Hz) and magnetometer data (20Hz) for 60 seconds from four different boards connected to the same integrated bluetooth antenna of RaspberryPi 3 model B. The expected number of samples is 1500 for accel and gyr, 1200 for magn.
When I use the integrated bluetooth antenna of my Lenovo Z50-70 laptop the number of samples is correct (they are the expected number minus an error of 1%).
When I run the code on the RaspberryPi the results are very bad. The relative error is bigger than 1%.
What did I do wrong?