So I have had my Roku Express for about 6 months. It has been hooked up to the same tv on the same wifi the entire time, but recently stopped connecting to the internet. It will connect to my wifi, but then immediately disconnects, while simultaneously saying the signal strength is excellent. When I check the connect it says the playback speed is poor. However, I have a different Roku in a different room, connected to the same wifi that is having no problems. The one I'm having issues with is actually closer to the router so this makes no sense. I have reset both the Roku and the Router several times and nothing is working. I was actually able to connect it to my hotspot on my phone but I can't keep doing that, I need to get it to connect to wifi.
I've never been able to pin it down exactly, but I *think* my internet connection problems usually occur when my internet service goes down while I'm actually streaming something. Even though the internet may come back up in a short period of time, it seems to have somehow killed the connection settings on my Roku.
This has always worked for me to fix wifi problems. The order you do things can be important:
If that doesn't fix it, try disconnecting the power to your Roku for a few seconds. When it comes back up, see if you then can set up the network connection.