Merge pull request #13858 from nextcloud/backport/13857/stable31

[stable31] Feat: add link to required remote servers in system requirements

Author: nickvergessen

admin_manual/installation/harden_server.rst

@@ -250,6 +250,8 @@ security headers are shipped.
 .. _Web TLS Profiler: https://tlsprofiler.danielfett.de/
 .. _RFC 4086 ("Randomness Requirements for Security"): https://tools.ietf.org/html/rfc4086#section-5.2
 
+.. _connections_to_remote_servers:
+
 Connections to remote servers
 -----------------------------
 

admin_manual/installation/system_requirements.rst

@@ -40,6 +40,8 @@ For best performance, stability and functionality we have documented some recomm
 
 See :doc:`source_installation` for minimum PHP-modules and additional software for installing Nextcloud.
 
+To ensure the full functionality of your Nextcloud, please make sure that the server can reach the :ref:`required remote systems<connections_to_remote_servers>`. 
+
 CPU Architecture and OS
 ^^^^^^^^^^^^^^^^^^^^^^^
 A 64-bit CPU, OS and PHP is required for Nextcloud to run well.