PHP SoapClient __lastRequestHeaders突然停止生成

Question

I have a problem with PHP's SoapClient.

After approximately 1015 successful requests it suddenly stops generating headers and requests. Underneath a bit of code.

$this->client = new SoapClient($this->location . '?wsdl', array('trace' => 1));

$result = $this->client->__doRequest($xml, $this->location, $dienst, 1);

for the first 1015 __lastRequestHeaders gives me a text output.

 echo "RequestHeaders:
" . $this->client->__getLastRequestHeaders() . "
";
 echo "Request:
" . $this->client->__getLastRequest() . "
";
 echo "ResponseHeaders:
" . $this->client->__getLastResponseHeaders() . "
";
 echo "Response:
" . $this->client->__getLastResponse() . "
";

After 1016 requests it outputs nothing (except the fixed textlabels) and the soaprequest is not created.

The remote server claims not to limit the amount of connections made. This is also the case on our servers.

Even if I wait for 30 minutes after 1000 requests or even 200 requests. It always seems to stop after 1015 successes.

I must be missing something here. a config setting or something like that. I'm using Ubuntu 16 and PHP7.