It is either one of three things.
1. The PlayOn!HD not working correctly through a software or a hardware problem (a bad network port).
2. A bad internet cable. It might be broken or you are using a crossover cable instead of a patch cable. Not all routers will auto sense the 1,2 and 3,6 transmit and receive pairs and reverse them.
3. Your router has an issue. Perhaphs it has DHCP turned off or you have MAC access control turned on. This is one provided by your telco company that happens to be your ISP as well I think.
Things I would do:
- Log into your router from your PC and check to make sure DHCP is on
- Plug in the network cable into the PlayOn!HD and then turn it on from being completely off (power unplugged)
- See if the PlayOn!HD comes up as a user on the router
- Use another network cable to connect the two and use another port on the router
- Double check that you do not have media access control turned on in the router (MAC address ontrol)
- Update the firmware on the PlayOn!HD to make sure there is not an issue with a corrupt flashing (stranger things have happened)
- Eliminate the PlayOn!HD as the issue by plugging it into someone else's network