You may need to open ports in the firewall to allow incoming connections and messages. For example, on Linux:
sudo apt-get install ufw
sudo ufw allow 10000/tcp sudo ufw allow 10000/udp
sudo ufw status sudo ufw status verbose sudo ufw status numbered sudo ufw delete <number>
1. Python 2 on a Raspberry Pi seems to have a problem receiving UDP messages. Use Python 3.
2. The Raspberry Pi seems to miss messages when several UDP messages sent to it rapidly. (Remember it is a small computer.)
3. TCP/IP seems to work.