Continuing my issue from [this][1] thread.


  [1]: https://magento.stackexchange.com/questions/372871/varnish-not-working-with-magento-2-4-3-website-doesnt-response/

I think it's not caching due to Cache-Control header. Firstly, let me share my updated VCL configuration below maybe my VCL has an issue somewhere.


    vcl 4.0;

    import std;
    include "./vars.vcl";
    include "./pagespeed-requirement.vcl";

    sub vcl_recv {
    if (req.restarts > 0) {
        set req.hash_always_miss = true;
    }

    if (req.http.host ~ "www.domain1.com" || req.http.host ~ "domain1.com") {
        set req.backend_hint = domain1;
        return (pass);
    } else if (req.http.host ~ "www.domain2.com" || req.http.host ~ "domain2.com") {
        set req.backend_hint = domain2;
    } else if (req.http.host ~ "career.domain3.com") {
        set req.backend_hint = career;
        return (pass);
    } else {
        set req.backend_hint = default;
        return (pass);
    }
    
    if (req.url ~ "^/.well-known/") {
      return (pass);
    }
    
    # Remove the proxy header to mitigate the httpoxy vulnerability
    # See https://httpoxy.org/    
    unset req.http.proxy;


    if (req.method == "PURGE") {
        if (client.ip !~ purge) {
            return (synth(405, "Method not allowed"));
        }
        
    # capistrano-magento2 gem for purging old content from varnish during it's deploy routine.
        if (!req.http.X-Magento-Tags-Pattern && !req.http.X-Pool) {
            return (synth(400, "X-Magento-Tags-Pattern or X-Pool header required"));
        }
        if (req.http.X-Magento-Tags-Pattern) {
          ban("obj.http.X-Magento-Tags ~ " + req.http.X-Magento-Tags-Pattern);
        }
    # ban everything to catch assets as well
        if (req.http.X-Magento-Tags-Pattern == ".*") {
          ban("req.url ~ .*");
        }
        if (req.http.X-Pool) {
          ban("obj.http.X-Pool ~ " + req.http.X-Pool);
        }
        return (synth(200, "Purged"));
    }

    if (req.http.X-Forwarded-Proto !~ "https") {
        set req.http.location = "https://" + req.http.host + req.url;
        return (synth(750, "Permanently moved"));
    }

    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 customer, shopping cart, checkout
    if (req.url ~ "/customer" || req.url ~ "/checkout" || req.url ~ "/payment" || req.url ~ "/reclaim" || req.url ~ "/search" || req.url ~ "/order-confirmation-summary") {
        return (pass);
    }

    # Bypass health check requests
    if (req.url ~ "/health_check.php") {
        return (pass);
    }

    # Set initial grace period usage status
    set req.http.grace = "none";

    # 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|webp|png|gif|gz|tgz|bz2|tbz|mp3|ogg|swf|flv|webp)$") {
            # 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 {
            # unknown algorithm
            unset req.http.Accept-Encoding;
        }
    }

    # Remove all marketing get parameters to minimize the cache objects
    if (req.url ~ "(\?|&)(gclid|cx|ie|cof|siteurl|zanpid|origin|fbclid|mc_[a-z]+|utm_[a-z]+|_bta_[a-z]+)=") {
        set req.url = regsuball(req.url, "(gclid|cx|ie|cof|siteurl|zanpid|origin|fbclid|mc_[a-z]+|utm_[a-z]+|_bta_[a-z]+)=[-_A-z0-9+()%.]+&?", "");
        set req.url = regsub(req.url, "[?|&]+$", "");
    }

    # Static files caching
    if (req.url ~ "^/(pub/)?(media|static)/") {
        # Static files should not be cached by default
        return (pass);

        # But if you use a few locales and don't use CDN you can enable caching static files by commenting previous line (#return (pass);) and uncommenting next 3 lines
        #unset req.http.Https;
        #unset req.http.X-Forwarded-Proto;
        #unset req.http.Cookie;
    }

    # Authenticated GraphQL requests should not be cached by default
    if (req.url ~ "/graphql" && req.http.Authorization ~ "^Bearer") {
        return (pass);
    }

    return (hash);
    }


    sub vcl_hash {
        if ((req.url !~ "/graphql" || !req.http.X-Magento-Cache-Id) && 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);
    }
    
    if (req.http.cookie ~ "currency=") {
    set req.http.X-TMP = regsub(req.http.cookie, ".*currency=([^;]+);.*","\1");
    hash_data(req.http.X-TMP);
    unset req.http.X-TMP;
    }

    if (req.url ~ "/graphql") {
        call process_graphql_headers;
    }
    }

    sub process_graphql_headers {
    if (req.http.X-Magento-Cache-Id) {
        hash_data(req.http.X-Magento-Cache-Id);

        # When the frontend stops sending the auth token, make sure users stop getting results cached for logged-in users
        if (req.http.Authorization ~ "^Bearer") {
            hash_data("Authorized");
        }
    }

    if (req.http.Store) {
        hash_data(req.http.Store);
    }
    if (req.http.Content-Currency) {
        hash_data(req.http.Content-Currency);
    }
    }

    sub vcl_backend_response {
    set beresp.grace = 3d;

    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;
    }

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

    # 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);
    }

    # validate if we need to cache it and prevent from setting cookie
    if (beresp.ttl > 0s && (bereq.method == "GET" || bereq.method == "HEAD")) {
        unset beresp.http.set-cookie;
    }

       # 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.Cache-Control ~ "no-cache|no-store") ||
           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";
            set resp.http.Grace = req.http.grace;
        } else {
            set resp.http.X-Magento-Cache-Debug = "MISS";
        }
    } else {
        unset resp.http.Age;
    }

    if (obj.hits > 0) {
        set resp.http.X-Cache = "HIT";
        set resp.http.X-Cache-Hits = obj.hits;
    } else {
        set resp.http.X-Cache = "MISS";
    }

    # Not letting browser to cache non-static files.
    if (resp.http.Cache-Control !~ "private" && req.url !~ "^/(pub/)?(media|static)/") {
        set resp.http.Pragma = "no-cache";
        set resp.http.Expires = "-1";
        set resp.http.Cache-Control = "no-store, no-cache, must-revalidate, max-age=0";
    }

    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;
    }
    
    sub vcl_synth {
    if (resp.status == 750) {
        set resp.http.location = req.http.location;
        set resp.status = 301;
        return (deliver);
    }
    }
    
    sub vcl_hit {
    if (obj.ttl >= 0s) {
        # Hit within TTL period
        return (deliver);
    }
    if (std.healthy(req.backend_hint)) {
        if (obj.ttl + 300s > 0s) {
            # Hit after TTL expiration, but within grace period
            set req.http.grace = "normal (healthy server)";
            return (deliver);
        } else {
            # Hit after TTL and grace expiration
            return (restart);
        }
    } else {
        # server is not healthy, retrieve from cache
        set req.http.grace = "unlimited (unhealthy server)";
        return (deliver);
    }
    }


We need to focus on domain2, the Cache-Control headers in response headers are `max-age=0, no-cache, no-store`. No custom code has `cacheable=false` in Magento's `app/code` directory. Hence, I don't know how is this being added. 

I commented the following lines in vcl_backend_response and was able to see `X-Cache: HIT` on the browser only for the `/` home page. Other page's don't have this parameter at all.

     if (beresp.ttl <= 0s ||
           beresp.http.Surrogate-control ~ "no-store" ||
           (!beresp.http.Surrogate-Control &&
           beresp.http.Cache-Control ~ "no-cache|no-store") ||
           beresp.http.Vary == "*") {
            # Mark as Hit-For-Pass for the next 2 minutes
            set beresp.ttl = 120s;
            set beresp.uncacheable = true;
        }

Upon checking the logs for command:

    varnishlog -g request -b -i BeReqUrl -I BerespHeader:Cache-Control \
    	-I BerespHeader:Expires -I BerespHeader:Vary -I BerespHeader:Set-Cookie \
    	-I BerespHeader:Surrogate-Control -i TTL -q "TTL[6] eq 'uncacheable'"

I get following result for the main domain/home page. (https://www.domain2.com).

    **  << BeReq    >> 65569     
    --  BereqURL       /
    --  BerespHeader   Cache-Control: max-age=0, no-cache, s-maxage=60
    --  TTL            RFC 60 10 0 1724061342 1724061342 1724061342 0 60 cacheable
    --  TTL            VCL 60 259200 0 1724061342 cacheable
    --  TTL            VCL 120 259200 0 1724061342 cacheable
    --  TTL            VCL 120 259200 0 1724061342 uncacheable
    --  BerespHeader   Vary: Accept-Encoding
    

Also, there are no logs if I click on another category page or product, it's as there was never made a request and `x-cache` is also missing in response headers. Probably all other pages/paths are being bypassed.

P.S: I am also getting Warning on browser/network tab:
"Cookies for this request are blocked due to third-party cookie phaseout."