In the Intranet environment, the interface on the test server fails to connect. The returned information is as follows:

Unable to connect to remote host: Connection refused

The server system is Ubuntu 16.04. If you use sudo UFW disable to shut down the firewall, you still can’t because of iptables

According to the method described in the following article

https://blog.csdn.net/zuifeng503/article/details/8209441

Just use the following command to turn off iptables

sudo iptables -P INPUT ACCEPT  
sudo iptables -P FORWARD ACCEPT  
sudo iptables -P OUTPUT ACCEPT  
sudo iptables -F