The slingbox can use more then just port 5001. With the newer slingbox 500 and 350 it defaults to this automaticlly. Only if the router has used port 5001 will it go to the next port like 5002. Legacy unit's such as AV, SOLO, Pro, & Pro HD will let you change that port in the setup internet viewing test.
SlingMedia Technical Support
I see that you have port forwarded to port 443. If the Slingbox is still showing 5001 still you need to go into setup internet viewing. When it fails click next or manual configure it should show you the IP address and Port to the left of the screen. You will see edit under these items click this area you will be able to change port to 443 then save information and then run test again. If it passes the test you will be all set.
Sling Media Moderation Team