I posted this in the Audio/Video Troubleshooting section for the Slingbox 350, but I thought I would post it in the general section for the 350 as well.
I'm new to Slingbox. I bought a Slingbox 350, set it up without issues and played it on our 2nd TV through our Amazon Fire TV Slingplayer app. Picture was clear and motion was smooth even on action scenes. Next day, the video on the Fire TV was not smooth but appeared to buffer faster action scenes ('jumpy' image). I checked network speeds, direct wired Ethernet cables, contacted support and they recommended I exchange the box. I did check the firmware versions right after setting it up and the following day. Out of the box was vs 1.4.122 when I didn't have a problem; over night it updated to 1.5.072 and this is when I experienced the problems on the Fire TV. I exchanged the Slingbox 350 for another one and the same thing happened. Immediately after setting it up, I checked the firmware version and it was 1.4.122; the picture on the Fire TV Slingplayer app was smooth even on action scenes. The next morning, the streaming was back to being 'jittery' with noticeable buffering on action scenes. I checked the firmware on the Slingbox and it had updated to 1.5.072 overnight. I checked the picture quality from my PC and it was perfectly smooth. It appears that the latest firmware update 1.5.072 is not producing the same smooth streaming on the Fire TV Slingplayer app than the previous firmware version 1.4.122.
Just to clarify, when I say that there appears to be buffering, I mean that the image tends to be discontinuous and 'jump' rather than be smooth transitions during action scenes; the picture doesn't get 'stuck' or have long buffering times as others have mentioned, it mainly tends to jump rather than have smooth transitions. If there are no fast motions, then no problem. The best TV program to experience this is by watching Modern Family. There is a lot of camera motion on this program and with this rapid motion, the images have a tendency to jump rather than be smooth movements. Also, it does not have this effect when watching on my PC using Slingbox Watch. It is on the Fire TV Slingplayer app only. I have read that on previous Slingplayer apps (and previous Slingboxes) that there were setup choices to improve the smoothness of the action which might cause the picture to be somewhat 'softer' instead of crisp as a trade off. This is what seems to be happening, only there are no adjustments on the Fire TV Slingplayer app for this; so I'm wondering if they did this with the most recent firmware update automatically together with the Fire TV Slingplayer app. The image is very crisp; however, action scenes definitely tend to jump rather than be smooth; and I didn't experience this before the firmware update when watching on the Fire TV Slingplayer app.
I'm interested if Sling can acknowledge that this may have been a change that they automatically made in the update (rather than give the users some setup control to control the smoothness of the action) and if there are at least plans to fix this. The image is perfect otherwise, very crisp and definitely HD, just looking to smooth out the action. The concept of this box is great and I hope to make more use of it but hopefully with a smoother image. Also, I'm interested if other Slingbox 350 users experience this with the firmware change when viewing on the Fire TV Slingplayer app.