AirPort Extreme routing speed reduced via AT&T Gigapower

[fhturner]

Hey Everyone—

Got a weird one here. Back in mid-2017, we got the 1000Mbps x 1000Mbps AT&T GigaPower service. This has been routed (NAT, default host, DNS) via an AirPort Extreme 802.11ac base station, and has worked great. I've regularly speed-tested at >850Mbps both ways**. However, recently, I've started getting a very consistent cap of only 50Mbps down and around 300-400Mbps up.

I swapped in another AirPort Extreme, applied the same config, and saw the same weird behavior. Moving a client device from the AP Extreme to plugged directly into the AT&T modem w/ the same cable results in 850Mbps+ up and down again. I also tested reconfiguring the AP Extreme into Bridge mode, rather than routing, and saw the full speed return. So, basically, the AirPort's routing is throttling the connection for some reason. The weird part is that I haven't changed anything and this has only recently occurred.

Might something have changed on the AT&T gateway to cause some sort of conflict w/ the AirPort's routing? If so, what to try changing on the gateway (it's a Pace 5268AC). Again, this has worked perfectly exactly as is for around a year and a half. Suggestions for further testing/comparisons? Of course I have done all the basic things like power-cycling devices...

Thx,
Fred

** = I am performing all of these observations and tests via WIRED connection, so I'm not really concerned about falloff when on WiFI...just optimizing the wired routing.

 

[BrianBaughn]

What changes do you make on the AT&T modem when you use the AE for routing?

 

[Howard2k]

From a pure routing perspective it shouldn’t change anything, since you’re not running a routing protocol between the devices. (Well, I’m assuming you would have mentioned it if you were).

You say you applied the same configuration and saw the same result. So my guess is that you have something in place that is taxing the AP CPU. Perhaps encryption, VPN, or advanced logging.

It maybe there is some QoS setting that is driving this behaviour.

So with the new AP and without restoring configuration, factory reset and configure from scratch, does the issue still occur? And if so, what exactly did your configure?

Does it occur on LAN to LAN as well as LAN to WAN?

 

[fhturner]

Just to follow up on this, it turns out it isn't the AirPort's routing speed at all. Further testing showed that it has to do with configuring the U-verse gateway to pass through its WAN IP to a local device. I connected a MacBook Pro straight to the gateway, picking up an internal 192.168.x.x IP address, and it was hitting top speed (850Mbps+). As soon as I changed the gateway config to provide the WAN IP to the MacBook, the speed dropped to what I was seeing via the AirPort: max 50Mbps down and 300-400Mbps up.

There must have been a recent software push on the gateways that is causing this. Not long ago (a couple of months maybe), I was getting full speed w/ the WAN IP passed through to my AirPort Extreme. The AT&T tech that came out is supposedly going to inquire to some colleagues about this. Appears to be a bug to me at this point...