diff --git a/README.md b/README.md
index ef7e1db..6e36f95 100755
--- a/README.md
+++ b/README.md
@@ -5,25 +5,24 @@ This TYPO3 extension is a flexible and generic way to track the pages that are c
 nginx or varnish, or any useful CDN.
 
 Currently supported backends / providers:
- * Cloudflare CDN
- * Fastly CDN
- * Varnish via curl
- * plain curl
+ * Cloudflare CDN (https://packagist.org/packages/b13/cloudflare-cdn)
+ * Akamai CDN (https://packagist.org/packages/b13/akamai)
+ * Azure CDN (https://packagist.org/packages/b13/azure-purge)
 
 What does it do?
 ----------------
 By embracing TYPO3's Caching Framework this extension provides a new cache to track all pages outputted that are
 "cacheable". When an editor changes content on a page, the page cache needs to be cleared - and the CDN / reverse proxy
-needs to be informed that the cache is invalid. This is usually done via a HTTP PURGE request to the CDN / proxy server.
+needs to be informed that the cache is invalid. This is usually done via a HTTP PURGE request to the CDN / proxy server
+or a custom API.
 
 The benefits for that are that the editor does not need to worry why out-of-date information is still visible
 on his/her website.
 
 Requirements
 ------------
- * A TYPO3 setup (v9 LTS+) with cacheable content, see the "cacheinfo" extension for what can be tracked with HTTP caches.
- * Either nginx or varnish configured to proxy the TYPO3 system. For nginx, make sure that nginx is compiled to allow
- to flush caches via HTTP `PURGE`. Alternatively, use a CDN like Fastly or Cloudflare for playing around with it.
+ * A TYPO3 setup (v11 LTS+) with cacheable content, see the "cacheinfo" extension for what can be tracked with HTTP caches.
+ * A CDN or Reverse Proxy (such as nginx or apache2)
 
 Setup
 -----
@@ -36,27 +35,7 @@ Whenever a cacheable frontend page is now called, the full URL is stored in a ca
 table is emptied completely, additionally, a HTTP PURGE call to the reverse proxy is made to empty all caches.
 If only a certain tag is removed, the PURGE call is made only to the relevant URLs that are stored in the cache.
 
-### Fastly
-
-Fastly makes a direct HTTP PURGE call to a specific URL, so it needs to be ensured that the request comes directly
-from the production environment (CDN backend server) where access to fastly is allowed, and PURGE requests are accepted.
-
-Ensure to set the environment variables `FASTLY_SERVICE_ID` and `FASTLY_API_TOKEN`.
-
-### Cloudflare
-
-Cloudflare v4 API is used to make HTTP requests via Guzzle HTTP and API Tokens. This is done by firing HTTP POST
-requests to purge one, multiple or all requests on a domain.
-
-Ensure to set the environment variable `CLOUDFLARE_API_TOKEN` in place.
-
-#### Configuration
-
-Add this to your `AdditionalConfiguration.php` file:
-
-    $GLOBALS['TYPO3_CONF_VARS']['EXTCONF']['proxycachemanager']['cloudflare']['zones'] = [
-        'example.com' => 'MY_ZONE_ID'
-    ];
+### Configuration
 
 By default all administrators can flush the CDN caches via the toolbar
 on the top right corner of TYPO3's Backend.
@@ -70,12 +49,9 @@ UserTsConfig option:
 
 `options.clearCache.proxy = 0`
 
-#### Limitations
- - Only API Token authentication is available
- - It is not possible to flush by tag (Enterprise Only)
-
 Credits
 -------
+
 The extension was created taken all the great from Andreas Gellhaus, Tom Rüther into account, as well
 as `moc_varnish` and `cacheinfo` as great work before.
 
diff --git a/UPGRADE.md b/UPGRADE.md
new file mode 100644
index 0000000..50202b8
--- /dev/null
+++ b/UPGRADE.md
@@ -0,0 +1,38 @@
+# Upgrade Instructions
+
+v3 => v4
+
+Proxycachemanager v3 served for many years as a well thought out basis
+for extending the interface for any kind of proxy and CDN adapter.
+
+However, some functionality has been removed and adapted,
+here is a list of features that have been removed or changed:
+
+## Removed Functionality
+
+* Cloudflare CDN Cache Provider
+* Curl HTTP Cache Provider
+* Fastly CDN Cache Provider
+* Varnish HTTP Cache Provider
+
+These features can be added in separate extensions requiring
+proxycachemanager, and utilizing even more functionality.
+
+In case you need them, we suggest moving the code from "proxycachemanager"
+v3 into your extension code, and then adapt to the updated
+interface.
+
+## Adapted "ProxyProviderInterface"
+
+The main interface "ProxyProviderInterface" has the following methods removed:
+
+* "setProxyEndpoints" - Not every Cache Provider ships an endpoint, so this can be handled individually
+* "flushCacheForUrl($url)" - Use "flushCacheForUrls(array $urls): void" instead
+
+New methods have been introduced:
+* "isActive(): bool" to define if a Proxy Cache Provider has been set up properly
+* "shouldRequestBeMarkedAsCached(RequestInterface $request): bool" allows to define whether a frontend page is behind a reverse proxy and should be added to the cache
+
+In addition, the interface is now fully typed.
+
+The TYPO3 Extension now required PHP 8.1 and TYPO3 v11 LTS.
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