ONT to AirPort Extreme without ISP router

What happens if you connect the ONT directly to a Mac or PC using an Ethernet cable? (Turn off the Wi-Fi on the computer to test).

If there is also no Internet connection this way......as I suspect.....this tells you that either the ONT has been configured to only work with the Vodaphone router......or....there is a special setting on the Vodaphone router that allows it to interface with the ONT.

If the latter.....there is no specific setting on any AirPort router that would allow it to connect to an ONT.

PPPoE settings on the AirPorts are ancient.....designed to work with older DSL systems. Fibre was unknown at the time. Apple never updated PPPoE settings on the AirPorts, so you are working with 15 year old technology.

I suppose it is possible that PPPoE could work, but as a I mentioned earlier, there are no settings or adjustments on an AirPort for a fibre connection.

The AirPort will work directly with an ONT provided by Verizon in the U.S., but you have to have a Verizon tech out to get into the ONT to make the modifications. When this is done, a regular Ethernet connection is delivered to the AirPort and the AirPort is set up to Connect Using Ethernet.....not PPPoE.

It looks like the signal at least has to pass through the Vodafone hub to work.

As it stands now, that is correct. I think the real question here is whether Vodafone is able and willing to modify the ONT. Most providers are less than thrilled to do this when asked.

Are 'passthrough' (bridge?) equivalents available?

I don't know, but I've never noticed anything like this.

Or is sticking with the Vodafone hub as the middle-man between the ONT and the AirPort Extreme the best way forward?

So far, this is the only way forward. The Vodafone will continue to be the "main" router in charge of the network and the AirPort will be configured as a "bridge" to offer Wi-Fi and Ethernet connections to the network.

If you want to go with Option 4 for now, you will have two Wi-Fi networks working at your house. I assume that you want to use the AirPort Wi-Fi, so you can either ignore the Wi-Fi signal from the Vodafone router or turn off the Wi-Fi function on the Vodafone if you can get into the settings on the product.

There might be information about this on a label on the back or bottom of the product.

In general, you have to enter something like 192.168.1.100.....for example only......into your browser and then enter the password for the device to get at the settings.