It's a network technology, so I'd start by disabling any firewalls you have operating. If that doesn't work, check your network setup. As a rule it's best to assign devices to the same IP group. For instance, all my equipment runs on.
192.168.1.xxx (192.168.1.64, 192.168.1.65, etc etc)
I've had problems in the past, where the router sometimes assigns devices to a different IP group, for example.
192.172.5.xxx
This has resulted in devices not being able to find each other.
For more information and suggestions please refer to your router manual.