Net Driver Listen Failure (Steam)

I have currently started following Unreal Engine’s Blueprint Multiplayer tutorial series. I got to the end of the 11th video, where they integrated Steam. After trying to test this, whenever I try to host a server, after a few seconds of working it brings me back to the first level and returns an error of ‘Net Driver Listen Failure’. Does anyone know how to fix this?

Note: I have enabled the Steam SubSystem plugin

Thanks!