The TD-8817 is a simple modem/router with one output. If you have connected directly to your tv it will not be easy to troubleshoot it. Have you connected it to a computer (directly or via a router switch), or is connected to a wireless router? You need to be sure it is working correctly on a computer. Next, are you sure that it is actually operational on your tv? the Sky+ box must be signed it to the router with a password. Finally, if your connected wirelessly, be sure your have s strong enough wireless signal getting to the tv.
There is a TP-Link helpline 24/7 on 0845 1470017 or at firstname.lastname@example.org