CentOS Apache PHP SoapClient has been working on it for a long time. It’s all about soap error failed to load external entity. If you take it out alone, there will be no problem in the execution of the command line. If you put it in the code, there will be another problem. After checking all kinds of possibilities, it can’t be solved. Finally, after a long time, a command appears

setsebool-Phttpd_can_network_connecton

So wait for about a few seconds, no error.