Airport Express amber flashing light

A persistent, flashing amber light indicates that any of the these potential conditions may require your attention:

1. The base station has not yet been configured because it is new, or it has been reset.
2. You have selected a security configuration that is not recommended.
3. A new firmware update is available for the base station.
4. One of several other conditions, such as a disconnected Ethernet cable or invalid IP address has been detected.

Ref:

• About the status light on AirPort base stations - Apple Support
• If your base station's light is flashing - Apple Support

To find out why your base station's status LED is flashing amber:

• Open AirPort Utility
• Click on the AirPort base station
• Look for a Status setting in the small window that appears. Note: Status only appears if there is an issue or notification.
• Click on the small amber dot there and another window will open to explain what the "issue" might be.

if you have issues getting airport util to find the express you can connect the express directly to your computer by Ethernet cable until you discover and resolve the cause of the amber light error mode

Netcomm wireless means you are in my part of the world.. using garbage routers lumbered on us by our only local manufacturer (who merely rebadge cheap stuff from everywhere else).

What model is the Netcomm.. look at the label underneath.. Something like NF18ACV would be a common one on NBN.

I'm not sure which Gen it is. Do you know how I can find out?

Old one looks like a Macbook power supply.. one ethernet port only. That is Gen1 (unless even earlier than that)

Later one but still old Gen2 has 2 ethernet ports and looks like old style airport extreme shrunk in the wash and dryer.

Sorry, but I don't know what bridge or router mean in terms of configuration. Can you tell me how I can find that out?

It's not connected by ethernet to our main router so it must be wirelessly.

Setup wirelessly is enough as it tells me you are in client mode.. This makes the airport behave just as a dumb device to pass airplay signal to your speakers which is what you want.

Would it be possible to use ethernet as it is much more reliable? Or perhaps you can buy a set of powerline adapters..again to help it behave reliably .. considering you are using netcomm main router.

You will need to reset the airport in order to get it back into your airport utility to configure it. But that may be becoming more difficult if it is old. Simply press the reset button on the airport express for about 10sec.. it will flash rapidly and wait for it to show up in the computer or iOS device.

To start with give us some details.

What is the main modem.. make and model? Is it also the main router?

If not what model is main router?

Is it a Gen1 or Gen2? Did you upgrade it to 7.8.1? When did you do that?

How is the Express configured? Bridge or router? Does it connect back to the main router by ethernet or wireless?

Reset the Express and it should allow you to reconfigure it.. at least for an hour or so you will have connection.

Then give us some screenshots from airport utility.. helps loads.

Are you using iOS or Mac to send the music?