When changing routers in the home, the Slingbox still looks for the previously network configuration. In order for your Slingbox to recognize the new router, you will have to do a Hard Rest to the Slingbox.
The article below will let you know how to do the rest:
After the reset is completed, don't forget to go back to setup.slingbox.com and reset up your Slingbox.
Hope this helps!!
Sling Media Moderation Team