Production environments have hardened security. If you’ve recently installed CRM on one of these environments you might come across this error:
A Sandbox Host is not available
Source: w3wp.exe (3940)
Sandbox Host: XYZ
Reason: System.ServiceModel.EndpointNotFoundException: Could not connect to net.tcp://xyz/CrmSandboxHost. The connection attempt lasted for a time span of 00:00:21.0254298. TCP error code 10060: A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond x.x.x.x:808.
The reason is that port 808 is not open on your backend server that’s running the sandbox service.
To fix this issue simply create a firewall rule to allow inbound TCP traffic on port 808.