AirPort Extreme and Full duplex

I had the same problem on my 3TB Time Capsule. Airport Utility on iphone Connection was showing Fair and half-duplex. I checked in the back of the box and the cable was connected to one of the top LAN ports, so I moved it to the bottom "WAN" port and voila, now Full Duplex.

In the air port utility it shows fair when in bridge mode and half duplex.

Can you do a screenshot to show me that. I have checked the utility but I cannot find anything that shows the status of a port as half duplex.

Any switch should default to full duplex. That is what switch means vs hubs. Hubs were half duplex devices and switches were full duplex. Any modern device with a switch chip is going to default to full duplex .. but it will negotiate the port speed and duplex nature of connection with the client it is connected to. Sometimes it can get it wrong..

It sounds like in your case a typical issue of the AC model which has negotiated wrongly.

While my older AirPort Extreme show full duplex in the airport utility, the new AirPort Extreme shows half duplex. Both airport extreme's were plugged into the same Ethernet cable.

That seems to be a bug in the new Extreme.. as Bob has noted use a switch in between your router and the TC and it might negotiate it correctly or use a crossover cable..

Before I get loud howls of protest.. this bug has been seen and this is pure pragmatism.. You do not need in this day and age crossover cables.. except they fix the bug. At least for some people.

See

Crossover cable to fix issue of connection to ONT or cable modem.

https://discussions.apple.com/thread/5391254?answerId=23236139022#23236139022&ac_cid=tw123456#23236139

I suspect Apple have a driver or actual hardware problem in the new AC version routers.

And so far .. it only affects the WAN port.. other ports are not being reported as having issues..

The best way to tell is use a managed switch.

I have a managed switch on my network which shows the speeds and duplex nature of all the ports.. these are not too expensive now.

The TC is on port 13 of the switch.

And I can quickly test all 4 ports .. all of which negotiate correctly to 1G Full..

But then I have a Gen4 not Gen5 TC.

Any way to turn on full duplex on the new AirPort Extreme ac manually?

Unfortunately no, since Apple removed this important setting in the 6.x versions of AirPort Utility.

You might want to try connecting the Ethernet cable to an Ethernet switch first, then connect another Ethernet cable from the switch, and then on to the WAN port on the AirPort Extreme to see if the switch will negotiate better than the AirPort Extreme.

Chances are, it will.

So my question is since the AirPort Extreme is showing half duplex in bridge mode is this half duplex just for the wan port?

There is no "WAN" port when the AirPort Extreme is configured to operate in Bridge Mode. All ports are LAN ports when the AirPort Extreme operates in Bridge Mode.

Are the 3 LAN ports full duplex and will my AirPort Extreme slow down as it shows half duplex when in bridge mode?

Sorry, I don't have the products here to be able to test this, so cannot give you an answer on that.