Cant access modem configurator

I wanted to add a MAC address to my PK5001Z. I could always reach the configuration program, indeed ID Safe kept the PW. Now FF & IE say they can't reach the modem. Pinging it works as does just reaching the Internet. I just went to my network map config and it sees the PK5001Z. I went to my old laptop and it saw the config program until N360 asked about sharing and it disappeared. So, obviously something is blocking my access. How do I get it back?