I have 5 Roku Devices in my home on various TV's. My LG TV Video seems to lag behind Video on other TV's in the home. Periodically it will stop what I'm watching and a small circle spins on the screen for a few seconds and eventually the video comes back. This puts the video behind my other TV's on the same program. My Wifi has been checked and it is Excellent.
That's the nature of streaming. There's no way to keep video synchronized across multiple devices.