SSL read: errno -5961

При отправке пост запроса с продакшн сервера curl возвращает ошибку

SSL read: errno -5961

Полный вывод:

*   Trying xxx.xx.xxx.xxx...
* TCP_NODELAY set
* Connected to my.site.ru (xxx.xx.xxx.xxx) port 443 (#0)
* Initializing NSS with certpath: sql:/etc/pki/nssdb
*   CAfile: none
  CApath: none
* loaded libnssckbi.so
* ALPN/NPN, server did not agree to a protocol
* SSL connection using TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA
* Server certificate:
*     subject: CN=*.site.ru,OU=PositiveSSL Wildcard,OU=Domain Control Validated
*     start date: May 16 00:00:00 2018 GMT
*     expire date: Jun 01 23:59:59 2019 GMT
*     common name: *.site.ru
*     issuer: CN=COMODO RSA Domain Validation Secure Server CA,O=COMODO CA Limited,L=Salford,ST=Greater Manchester,C=GB
> POST /site/url HTTP/1.1
Host: my.site.ru
Connection: keep-alive
Content-Length: 2589
Origin: https://my.site.ru
x-date-format: iso
User-Agent: Mozilla/4.0 (compatible; MSIE 5.01; Windows NT 5.0)
Content-Type: application/json
Accept: application/json, text/javascript, */*; q=0.01
X-Requested-With: XMLHttpRequest
Referer: https://my.site.ru/url
Accept-Encoding: gzip, deflate, br
Accept-Language: ru-RU,ru;q=0.8,en-US;q=0.6,en;q=0.4
Cookie: .ASPXAUTH=47568568CBC0C7D64E29AB1E4AF40B73B640472;
Expect: 100-continue
< HTTP/1.1 100 Continue
* We are completely uploaded and fine
* SSL read: errno -5961 (PR_CONNECT_RESET_ERROR)
* TCP connection reset by peer
* stopped the pause stream!
* Closing connection 0

PHP код :

    curl_setopt($curl, CURLOPT_URL, 'https://my.site.ru/url');
    curl_setopt($curl, CURLOPT_RETURNTRANSFER,true);
    curl_setopt($curl, CURLOPT_SSL_VERIFYHOST, false);
    curl_setopt($curl, CURLOPT_VERBOSE, true);
    curl_setopt($curl, CURLOPT_POST, true);
    curl_setopt($curl, CURLOPT_POSTFIELDS, $q);
    curl_setopt($curl, CURLOPT_CUSTOMREQUEST, "POST");
    curl_setopt ($curl, CURLOPT_CONNECTTIMEOUT , 0);
    curl_setopt($curl, CURLOPT_USERAGENT, "Mozilla/4.0 (compatible; MSIE 5.01; Windows NT 5.0)");
    curl_setopt($curl,CURLOPT_FOLLOWLOCATION,true);
    curl_setopt ($curl, CURLOPT_HTTPHEADER,$split);
    $out = curl_exec($curl);

На тестовых сборках проблему воспроизвести не смог.

Окружение CentOs 7, PHP 5.6, cURL 7.60