Very slow ATT fiber upload speed macbook pro since Sequoia

Does your premise hardware belong to ATT? If so, they may have pushed a firmware update to it that could have altered your delivery bandwidth on their side of the WAN or your LAN, or coincidentally, they are having delivery issues concurrently with your Sequoia upgrade. Check with them and see what they are reporting from a diagnostic to your location.

I don't have ATT service and my 360 Mbps Comcast service to my own DOCSIS v3.1 cable modem (Mot MB8611) or my Synology RT6600ax router — has not slowed after Sequoia v15 or v15.1 upgrade from the preceding Sonoma 14.7.1 on my M2 Mac Mini Pro with a Wi-Fi 6 connection. If there was an issue in Sequoia causing your network slowdown, seems as though it would not be unique to an ATT feed, but differences in Broadcom radios in our Macs may also be an issue here.

Yes, there may be something within Sequoia contributing to your decreased bandwidth with the network hardware in use. If it is a hard-to-define bug, only Apple will be able to fix it in a future release. All you can do in the interim is get an ATT response from the first paragraph and revisit your network hardware and macOS settings.

Ethernet is ok - good

Wifi not

Check the setting for the Wifi Connection

For some reason unknown to me

The Default setting is Rotating wifi address

Unfortunately the 2019 MBP does not support 6E

Say this as I run a Fibre Optic to Router with 500 / 500 Speed from ISP

When using 6E Wifi connection

Can get 1 GB + speeds Up and Down

As much as we appreciate the frustrations one ( you ) are having with the ATT Fibre Optic connections over Wifi .

There is not need to make this personal

As for removal of a posting

Only the Apple Moderation Team ( which I am not one of ) has the authority and right alter, edit or otherwise remove a posting

You remain welcome for the otherwise friendly and free suggestions

Do you have multiple Wi-Fi SSID or LAN segments defined for different older devices that may only offer lower bandwidth connections? Once in a great while, my M2 Mac mini Pro will connect to an 802.11g,n SSID instead of the expected 5 Ghz Wi-Fi 6 SSID. That drop in performance is telling…

Frank, you probably have already done so by now, but if not, power off your Mac with Sequoia, the router, and the ATT Fiber edge device, and then repower in reverse order. Probably won't change a thing, but worth a try.

Did you have ATT perform a diagnostic on their fiber line from their headend to your home? Again, probably nothing since your other devices appear to be achieving your bandwidth expectations.

In addition to the Comcast feed across the backyard, there is ATT Fiber, but I haven't been tempted…

Also, that 16-in 2019 MacBook Pro only has an 802.11ac radio which depending on your environment and potential interference will Tx out at 1300 Mbps (Wi-Fi) but more likely around 800 - 900 Mbps. The best speed I got from my 2020 Core i7 iMac with the same radio was 1300 Mbps and now, still running Monterey, it has slid to about 900 Mbps. My Synology RT6600ax router with six antennae is right next to it.

👍 and good luck