@alvaroav Dear all, Some advances by the end of the week. I have tried from a clean code, just building a new program. I come back to the option to open the socket, send all data in a loop, and at the end of the loop, close the socket. I am not so sure why, BUT now the ENOMEM error just appears from time to time. Moreover, I don't need any server (blocking or non-blocking) running. Moreover, I place this exception into the loop, and allow me to "reconnect" and continue the program even if an error appers. flag = 1 Nerrors = 0; socketUDP = socket.socket(socket.AF_INET, socket.SOCK_DGRAM) while (flag<200): time.sleep(0.05) data=bytes() data = data + b'counter = ' + bytes(str(flag),'utf-8') try: sent = socketUDP.sendto(data, addr) print(data) led.toggle() flag=flag+1 except OSError: Nerrors+=1 print('error ', Nerrors) continue socketUDP.close() I am thinking that the problem might come from the wifi connection to the router... I will check this next week. BR