I have a Verizxon FIOS router.
When the Slingbox Classic is not connected, my desktop computer gets average of 42mbps download/32 mbps upload (via speedtest.net).
When the Slingbox Classic is connected, I am lucky to get 2mbps each for download/upload speed.
This started happening just about less than a month ago.
Before that, I did not test the internet speed but I have no reason to because I got decent internet connection despite the Slingbox being connected.
I hope this could be resolved so I could keep using my slingbox which we have been enjoying for years now.