React native NSPOSIXErrorDomain Code=61 "Connection refused"

The last row of the error gives you a hint where to look:

Connection to http://localhost:8081/debugger-proxy timed out. Are you running node proxy? If you are running on the device, check if you have the right IP address in RCTWebSocketExecutor.m.

Additional information:

To debug on a real device: Open the file RCTWebSocketExecutor.m and change localhost to the IP address of your computer. Shake the device to open the development menu with the option to start debugging.

Even better, check the documentation that Facebook provides for Running On Device.

I've had issues before where the IP address was wrong but most recently I hadn't been able to resolve this issue until I simply turned off WiFi and then back on again.

Same network. Same IP. Who knows why but it worked for me ¯_(ツ)_/¯