Interestingly enough I used to have this issue a lot, but can't recall it happening for several months now. I'm using the lg650lb with the N3540 sound bar. Only two things I can think of thane have changed, bought a couple of powerline adaptors so my to is now connected via Ethernet rather than wifi, and also there have been several updates to the to since I last recall it happening.
For people it is still happening to, what happens if you turn off wifi on your television (regardless of how it's connected to the sound bar)?