Magento 2.1 – Varnish Cache Not Purging

I have a server with NGINX / Varnish 4 & Magento 2.1, I have setup everything need for varnish and Magento 2.1 in Stores > Configuration > Admin. Varnish is working.

My problem is that if I try to Flush Magento cache, the cache is not clearing. Varnish cache is purged only after restarting via ssh. On Magento developer documents I found somewhere that if /var/cache/ is empty then everything is working. In my case cache folder is not empty, I tried to delete but it comes back.

my server IP replaced by "server.ip"

env.php

 'http_cache_hosts' => array(
    array (
        'host' => 'server.ip',
        'port' => '6082',
    )
),

default.vcl

   vcl 4.0;

import std;
# The minimal Varnish version is 4.0
 # For SSL offloading, pass the following header in your proxy server or load balancer: 'X-Forwarded-Proto: https'

 backend default {
.host = "server.ip";
.port = "8080";
}

  acl purge {
"server.ip";
 }

  sub vcl_recv {
if (req.method == "PURGE") {
    if (client.ip !~ purge) {
        return (synth(405, "Method not allowed"));
    }
    if (!req.http.X-Magento-Tags-Pattern) {
        return (synth(400, "X-Magento-Tags-Pattern header required"));
    }
    ban("obj.http.X-Magento-Tags ~ " + req.http.X-Magento-Tags-Pattern);
    return (synth(200, "Purged"));
}

if (req.method != "GET" &&
    req.method != "HEAD" &&
    req.method != "PUT" &&
    req.method != "POST" &&
    req.method != "TRACE" &&
    req.method != "OPTIONS" &&
    req.method != "DELETE") {
      /* Non-RFC2616 or CONNECT which is weird. */
      return (pipe);
}

# We only deal with GET and HEAD by default
if (req.method != "GET" && req.method != "HEAD") {
    return (pass);
}

# Bypass shopping cart, checkout and search requests
if (req.url ~ "/checkout" || req.url ~ "/catalogsearch") {
    return (pass);
}

# normalize url in case of leading HTTP scheme and domain
set req.url = regsub(req.url, "^http[s]?://", "");

# collect all cookies
std.collect(req.http.Cookie);

# Compression filter. See https://www.varnish-cache.org/trac/wiki/FAQ/Compression
if (req.http.Accept-Encoding) {
    if (req.url ~ "\.(jpg|jpeg|png|gif|gz|tgz|bz2|tbz|mp3|ogg|swf|flv)$") {
        # No point in compressing these
        unset req.http.Accept-Encoding;
    } elsif (req.http.Accept-Encoding ~ "gzip") {
        set req.http.Accept-Encoding = "gzip";
    } elsif (req.http.Accept-Encoding ~ "deflate" && req.http.user-agent !~ "MSIE") {
        set req.http.Accept-Encoding = "deflate";
    } else {
        # unkown algorithm
        unset req.http.Accept-Encoding;
    }
}

# Remove Google gclid parameters to minimize the cache objects
set req.url = regsuball(req.url,"\?gclid=[^&]+$",""); # strips when QS = "?gclid=AAA"
set req.url = regsuball(req.url,"\?gclid=[^&]+&","?"); # strips when QS = "?gclid=AAA&foo=bar"
set req.url = regsuball(req.url,"&gclid=[^&]+",""); # strips when QS = "?foo=bar&gclid=AAA" or QS = "?foo=bar&gclid=AAA&bar=baz"

# static files are always cacheable. remove SSL flag and cookie
    if (req.url ~ "^/(pub/)?(media|static)/.*\.(ico|css|js|jpg|jpeg|png|gif|tiff|bmp|mp3|ogg|svg|swf|woff|woff2|eot|ttf|otf)$") {
    unset req.http.Https;
    unset req.http.X-Forwarded-Proto;
    unset req.http.Cookie;
}

return (hash);
}

sub vcl_hash {
if (req.http.cookie ~ "X-Magento-Vary=") {
    hash_data(regsub(req.http.cookie, "^.*?X-Magento-Vary=([^;]+);*.*$", "\1"));
}

# For multi site configurations to not cache each other's content
if (req.http.host) {
    hash_data(req.http.host);
} else {
    hash_data(server.ip);
}

# To make sure HTTP users don't see SSL warning
if (req.http.X-Forwarded-Proto) {
    hash_data(req.http.X-Forwarded-Proto);
}

}

 sub vcl_backend_response {
if (beresp.http.content-type ~ "text") {
    set beresp.do_esi = true;
}

if (bereq.url ~ "\.js$" || beresp.http.content-type ~ "text") {
    set beresp.do_gzip = true;
}

# cache only successfully responses and 404s
if (beresp.status != 200 && beresp.status != 404) {
    set beresp.ttl = 0s;
    set beresp.uncacheable = true;
    return (deliver);
} elsif (beresp.http.Cache-Control ~ "private") {
    set beresp.uncacheable = true;
    set beresp.ttl = 86400s;
    return (deliver);
}

if (beresp.http.X-Magento-Debug) {
    set beresp.http.X-Magento-Cache-Control = beresp.http.Cache-Control;
}

# validate if we need to cache it and prevent from setting cookie
# images, css and js are cacheable by default so we have to remove cookie also
if (beresp.ttl > 0s && (bereq.method == "GET" || bereq.method == "HEAD")) {
    unset beresp.http.set-cookie;
    if (bereq.url !~ "\.(ico|css|js|jpg|jpeg|png|gif|tiff|bmp|gz|tgz|bz2|tbz|mp3|ogg|svg|swf|woff|woff2|eot|ttf|otf)(\?|$)") {
        set beresp.http.Pragma = "no-cache";
        set beresp.http.Expires = "-1";
        set beresp.http.Cache-Control = "no-store, no-cache, must-revalidate, max-age=0";
        set beresp.grace = 1m;
    }
   }

 # If page is not cacheable then bypass varnish for 2 minutes as Hit-For-Pass
if (beresp.ttl <= 0s ||
    beresp.http.Surrogate-control ~ "no-store" ||
    (!beresp.http.Surrogate-Control && beresp.http.Vary == "*")) {
    # Mark as Hit-For-Pass for the next 2 minutes
    set beresp.ttl = 120s;
    set beresp.uncacheable = true;
}
return (deliver);
}

sub vcl_deliver {
if (resp.http.X-Magento-Debug) {
    if (resp.http.x-varnish ~ " ") {
        set resp.http.X-Magento-Cache-Debug = "HIT";
    } else {
        set resp.http.X-Magento-Cache-Debug = "MISS";
    }
} else {
    unset resp.http.Age;
}

unset resp.http.X-Magento-Debug;
unset resp.http.X-Magento-Tags;
unset resp.http.X-Powered-By;
unset resp.http.Server;
unset resp.http.X-Varnish;
unset resp.http.Via;
unset resp.http.Link;
}

curl -I -v –location-trusted http://server.ip/

 < HTTP/1.1 200 OK
 HTTP/1.1 200 OK
 < Date: Sun, 19 Mar 2017 19:01:06 GMT
 Date: Sun, 19 Mar 2017 19:01:06 GMT
 < Content-Type: text/html; charset=UTF-8
 Content-Type: text/html; charset=UTF-8
 < Keep-Alive: timeout=60
 Keep-Alive: timeout=60
 < X-Content-Type-Options: nosniff
 X-Content-Type-Options: nosniff
 < X-XSS-Protection: 1; mode=block
 X-XSS-Protection: 1; mode=block
 < X-Frame-Options: SAMEORIGIN
 X-Frame-Options: SAMEORIGIN
 < X-Magento-Cache-Control: max-age=86400, public, s-maxage=86400
 X-Magento-Cache-Control: max-age=86400, public, s-maxage=86400
 < Pragma: no-cache
 Pragma: no-cache
 < Expires: -1
 Expires: -1
 < Cache-Control: no-store, no-cache, must-revalidate, max-age=0
 Cache-Control: no-store, no-cache, must-revalidate, max-age=0
 < Age: 578
 Age: 578
 < X-Magento-Cache-Debug: HIT
 X-Magento-Cache-Debug: HIT
 < Connection: keep-alive
 Connection: keep-alive

curl -X PURGE

     <!DOCTYPE html>
  <html>
  <head>
<title>400 X-Magento-Tags-Pattern header required</title>
  </head>
  <body>
<h1>Error 400 X-Magento-Tags-Pattern header required</h1>
<p>X-Magento-Tags-Pattern header required</p>
<h3>Guru Meditation:</h3>
<p>XID: 65764</p>
<hr>
<p>Varnish cache server</p>
 </body>
 </html>