I usually use the chromecast device plugged into the tv's hdmi port, but I also have a roku streaming stick plugged into an hdmi port.
Sometimes my router's 2.4GHz connection craps out.
I discovered this about my Windows 10 computer
- Make sure you've switched your tv to the correct hdmi
- Click on the notifications area (to the right of the date in the bottom right corner of my windows display). It will show a rectangular window
- Click "connect" down at the bottom of the window
- You should see roku stick listed there. Click on it to connect
- You might see a message on your tv coming from roku to "accept" or "always accept." Click on one of those.