A firewall is blocking inbound traffic on TCP port 443, which is used by the Hosted Cache server for accepting incoming client ...

A firewall is blocking inbound traffic on TCP port 443, which is used by the Hosted Cache server for accepting incoming client offers to add content. As a result, clients cannot add content to the Hosted Cache. 
To create a Windows Firewall rule that allows inbound traffic on TCP port 443, run the command "Enable-BCHostedServer" from an elevated PowerShell command prompt. If a different firewall is used, modify the firewall settings to allow this traffic.