I was able to get it to work 2 ways.
1. I used the yellow composite video wire instead of the 3 component wires. Than I had to “reconfigure composite” in the sling setup menu.
Or
2. Switch from 1080p to 1080i on the Fios settop box. This allows you to use the 3 component wires and provides a clearer picture when using slingbox.
I did not notice any difference between 1080 p or I on my home TV.
To switch to 1080i go to settings/ video/ select 1080i from menu