[python] Errno 10061 : No connection could be made because the target machine actively refused it ( client - server )

The first: Please make sure your port '12345' is opening and then when you using a different network. You have to use the IP address in LAN. Don't use the 'localhost' or '127.0.0.1'. The solution here is: In server

host = '192.168.1.12' #Ip address in LAN network

In client

host = '27.32.123.32' # external IP Address

Hope it works for you