You can use the network assistant to setup manually the Internet Viewing feature. Even though your router is not listed, you can try a similar model, you will find more information at this article,
If your router isn't on the list, choose the one that is the most similar.
Example: If your router is made by Netgear, select that from the Router Brand menu. And then select the model that is most similar to yours.
Most router manufacturers do not change the administrative interface from model to model. If you choose one that is similar, this tutorial will probably work just fine.
If this doesn't work or if we don't even list your Router Brand, please tell us about your router. It will help us improve the Slingbox set up experience.
If the issue persists, you will need to check if the modem has a private IP as default gateway, in that case, it will be necessary to setup also the modem, have a look at this
Hope this helps
We need to get more details about your issue. Are you using the SlingPlayer Desktop version or Watch on Slingbox.com?
I recommend setting up the port forwarding rule on the router using this instructions:
After doing this, you just need to run manually the Internet Viewing setup and put the IP and the port number selected during the configuration of the router. For this, you can use the Setup Assistant on the SlingPlayer or at setup.slingbox.com.
Regards and hope this helps