First of all, please reset your device to default factory settings. You can do that by holding the reset button for about 5-6 seconds exactly.
After that, make sure you connect everything right. A cable going to WAN should be coming from your ISP firewall/gateway LAN port, and then the cable going from your LAN should be connected directly to the device you're trying to use.
Your PC then should be able to reach 192.168.1.1 address - if it doesn't, go to your Network Adapter settings and try using manual options of the connection.
IP: 192.168.1.X (anything like 192.168.1.5 or 192.168.1.100)
And preferred DNS: 192.168.1.1
Save the settings and you should be able to access your routers WebUI.
If there's anything else that troubles you - let me know in more details, I'll try to help you out.