Generally speaking a destination unreachable error means the outbound ICMP request message could not be routed to the destination. A timed out error means the request got to the remote end but the remote end was not able to get the ICMP response back to the local node.

This can happen for a number of reasons including the remote end having no route to the local node or (more likely in this case) there being an ACL in place somewhere that prevents the ICMP response packet from reaching the local node.