I am dealing with 2 issues with my Roku Express+. Have had it a little over 2 months and has been working just fine. Suddenly in the last couple days, I'm getting the error msg that the usb device does not have enough power even though it is plugged into the wall outlet. I have unplugged it, let it "reset;" sometimes for hours, plugged it back in, sometimes I'll get the same msg right away, sometimes I'll get a few minutes of play and then get the msg. Issue 2, have not had any internet connectivity problems with the wifi until the other situation has presented itself. Roku will power up but then can't find an internet connection. Any insight as to what is going on?
Assuming there is no issue with the power source (the wall outlet) then it certainly seems as if the power supply for the Roku is defective. That would cause all kinds of issues. It could be the device itself. Regardless, it may be advisable to return/exchange the device. You've had it for 2 months, which means it's still under warranty, so pursuing a repair/replacement (most likely it'll be replaced) would be in order.
Oh, if you have another Roku Express (or Express+) on another TV, you could swap the power supplies (or the Roku boxes) and see if the problem follows the power supply.
Basil https://www.basilsblog.com/ Roku Ultra (4660) Apple TV (5th gen), TiVo
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