Login to your router and go to WAN>>Multi-PVC and follow the screenshot below.
Tick P2~P4. Enable the port (P2, P3 or P4) only if the PC is going to connect iinet FetchTV
NOTES from iinet:
LAN addresses by DHCP server (your ADSL router should be the server).
DHCP must be enabled on the modem otherwise your fetchtv STB will not be assigned an IP address from your router.
If DHCP is disabled you will need to manually configure the IP address settings on your fetchtv STB – this is not recommended.