Express 4k+ connected to dumb TV. Two other roku devices in the house are working (different models). Morning of the issue turned TV on and there was displayed a vague message concerning software, there were no error codes. Went through a sequence of selecting a language, select wifi network, enter network password, green checkmark connected, spinning arrow with downloading message for about a minute, then message displayed Linking error /There was a problem connecting to the network. (actioniD:0 err:0:0) Please try again. Press the ok button to reconnect. Wifi signal strength is excellent. Connect a different roku device there it works.
I have done a power reset and a factory reset on the Express 4k+ and it just goes though the same above sequence.