This has happened with some router models that do some segregation of wireless/wired connections. The app will try to connect locally, but will be unsuccessful, so it will determine the device is offline.
You’ll need to switch to “Manual” in Dashboard > Remote Access, then change the ports, but do NOT add the ports in your Router’s port-forwarding section. This will force a Relay Connection, which should work remotely AND locally. Again, this is only for users experiencing local access issues.
Remote access issues are usually caused by something on the router blocking the connection. In some cases it is the remote network that is blocking the ports needed for remote access.