The Speedway isn't visible on your network because its IP address is set statically and its not in the same subnet at your router network.
Connect the Speedway directly to your laptop and set a static IP on the laptop for 192.168.1.1, then get to a command prompt and type ARP -a to see a list of attached devices. Use the MAC address to identify the Speedway. Change the laptop IP to the same subnet (192.168.1.xxx) with a different ending IP than the Speedway, and then you'll be able to connect to it using its IP address in your browser. From there, the IP can be changed.
Another approach is to reset the Speedway back to factory defaults using the reset button. This is all well documented on the Impinj web-site.