This is very odd since you only have this issue when you select the Internet Viewing setup. I'd like to know if the Slingbox is hardwired to the router using a Ethernet cable no longer than 7ft. If you are using a wireless or a power bridge, it will be necessary to connect the unit directly to the router just for the setup and then take it back to the other room. If the Slingbox is hardwired to the router you will need to Reset the Slingbox and confirm if you have the same situation running the Setup at Slingbox.com.
Hope this helps