PHP SoapClient: SoapFault exception Could not connect to host

using this code I make soap requests

$client = new SoapClient('http://example.com/soap/wsdl');

try {
    $result = $client->myMethod();
} catch (Exception $e) {
    echo $e->getMessage();
}

Sometimes (once out of ten), an exception is raised:

SoapFault exception: [HTTP] Could not connect to host

My attempts

1) I looked for solutions, and I read that this problem can be caused by wsdl cache, I disabled it in php.ini:

soap.wsdl_cache_enabled = 0
soap.wsdl_cache_ttl = 0

raises fewer exceptions

2) I tried to add to the host of windows (they are on windows) the resolution of the dns in windows/system32/drivers/etc/hosts:

160.XX.XXX.XX example.com

raises fewer exceptions

3) I also tried to disable "Windows Firewall",

raises fewer exceptions

4) I also tried to increase the default_socket_timeout in php.ini

default_socket_timeout = 90

nothing has changed

The question

The server soap does not seem to have problems.It is used without problems also from other sites. Is there anything else I can do?

My settings

PHP 5.6

Apache 2.4

Windows Server 2012

UPDATE

After many tests, I think that the problem is in the network, soap server is behind a reverse proxy, the problem appears in the proxy.

You need to improve your debugging efforts even further:

ad 1) Does the WSDL change a lot? If not, turn on WSDL caching. You don't need to connect to the server to fetch the WSDL file.

Is the output you mentioned really created in echo $e->getMessage();? You could add some debugging code inside the catch() block, for example:

• check if you can connect to the server in another way (for example file_get_contents($soap_url))
• if not, check what kind of error you are getting
  • print the time and check the error logs on the SOAP server
  • a 403 Forbidden or similar error points on a problem on the server
  • a Could not connect error points to a network problem (not exclusively but chances are higher for that)
• You could try to put it in a loop (something along the lines of for ($i = 0; $i <= 5; $i++) { /* ... */ sleep(1); continue; }) to see if a second try would make it work

All in all, "sometimes errors" are hard to debug, so either you should try to make it reproducible (which will point at the problem), or you need to record and output as much data as possible so that you can see where the problem was at the time when it occurred.