@Sador033
Depending on your apartment setup, the network may be configured using "isolation" rules. These are security settings that prevent devices from communicating with each other.
If you have access to your router and settings, you can try disabling and changing Firewall settings. In most routers, although called different things, you may have an "AP isolation" or "Wireless Isolation" setting normally under the Advanced Wireless Settings that you can enable/disable.
If you do not have access to the router (centrally managed by the apartment complex), then you may have to contact the admin and see if this can be configured for you. You can also try connecting to the Guest Network and see if isolation may not have been enabled on that band. In most cases, it will be enabled network wide, but some networks leave more freedom on the Guest Network bands so you may luck out and be able to connect your app to your TV.
Additionally, you "may" be able to get the mobile app to connect to an ethernet connected Roku device. If your device is ethernet capable, can try this alternate method.
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Now, there is a chance that it could simply be the mobile app. Try clearing out the app cache on your phone, restarting phone, and then try connecting again. However, I think it probably is more these isolation rules that are preventing you from interconnecting devices.
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