In the last few days my roku #3921rw would not be connected to the network. So now each time I want to use this device I have to power down a nearby wifi range extender and re power up the roku, Then the range extender can be powered back up. This was never an issue for the past say six months and all equipment is still in the exact same place as before this started. The only thing that may have changed is the roku update to 9.20 build 4131-91 with the bandwidth saver option - which I had tried it both with and without it being disabled.
Note: and no there has not been any recent firmware update(s) on any of the network gear.