If you have access to another wifi net, like maybe a mobile phone hotspot, you could set up using that. Once set up, Settings > System > About will give you the MAC address. Then you can set up with your router and reset your Roku's network settings for its new net.
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Roku Streaming Stick+ 3810 | TCL Roku TV 43S245/C107X | Roku Streaming Stick 3600
