By chance I've checked the "receiver range" function on customglobal site. That is what I get selecting my custom port (51005). It appears definitely out of scale, any idea about what is wrong with it?
VRS issue, receiver ranges are not reset every day so you can see even accidentally tracked aircrafts. Below screenshot from my own VRS (MDA-03 range):
Thanks, leave it as it is, it was just curiosity. A question: can I stream data from more than one raspi at same time on my custom port?
You can't .. one stream one port is how it works. Grab another custom port; We're going to have to expand it soon here for more feeds.