My Roku Ultra will not connect via wireless or ethernet. When I try to connect via Ethernet I get an error message stating “cannot detect Ethernet cable” even though the cable is connected. When I try to connect via Wi-Fi I get a message stating “unable to connect to wireless network.”
Is this a new Roku ultra? Did you try unplugging it for 60 seconds and plugging it back in? Did you restart your router and modem? Unplug those for at least 60 seconds also
When you plug in the Ethernet cable do you see a green light on the back of the Ultra by the cable? If not, it's not connected, the cable is bad, or the Ethernet port on either the Ultra or whatever you're connecting the other end to is bad.