Roku 3 remote does not use Bluetooth.
If it's WiFi then, is there a way for me to know which band it's using?
In either case, nothing's changed in my living room as far as WiFi interference is concerned. The distance between the remote and the puck is maybe 6 feet.
Not seeing where you checked your battery level. Always start simple and go from there. We need to rule that out.
Your distance is less than mine on my Roku 3 (actually Roku 2 model 4210, which is identical to a Roku 3; truly the same device).
If you are running a WiFi network — I assume you are, just not connecting the Roku to it — check your router and see what channel it’s using for 2.4 GHz. Probably 6, 1, or 11. Try changing it to another one of those. No need to try others. Those 3 don’t overlap, and you’ll want the one with less interference from all the signals bouncing around from your equipment, from the neighbors, and from everywhere else.
Let us know how that goes.