@Nhklobuchar
From Settings/Network/About, are you seeing both a MAC address and an IP address. (are either one of these all zeros?)
If you have MAC address, try performing a Network Connection Reset on the RokuTV and restart your router. (Settings/System/Advanced System Settings/Network Connection Reset/Reset Connection).
Also, check on the RokuTVs that are working for the wireless channel number. (Settings/Network/About). Is the suspect RokuTV using the same wireless channel number? Basically, checking to see if all your working RokuTVs and the suspect RokuTV are connecting to same band of your home network. (2.4ghz or 5ghz)
What is your router model number, and who is ISP (internet service provider)?
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Roku Community Streaming Expert
Just another Roku user... I am not a Roku employee.
Insignia RokuTV, Ultra 4660, Premiere+ 3921, Express 4k+ 3941, Streambar 9102