Stuttering But not always

I use version 1.2.1 on a very strong Desktop wire-connected to the N type router. My 3 Samsung T.Vs are wirelessly connected ( 2 D6600, 1 D5000) In both D6600 ( which are a bit topographically farther than the D5000) I experience a lot of stuttering at times. BUT - watching the same movie at a different arbitrary time can result in a perfectly smooth watch.

I did not find any reference to that in the Board groups. Any suggestions of what can be the reason for this behavior?

[ I did try fiddling with changing router RF channels -> to no avail , verified that the computer is not loaded-> NO LOAD at all ]