1 gig to gateway but sub 250 Mbps to devices?

This is a direct result of Comcast's network management practices, whereby they limit/throttle/restrict/impede throughput to specific destinations and from specific user agents.

While their service is capable of and has performed at or near gigabit speeds, this is only true in specific scenarios. However, in practice such as the day-to-day use of browsers/mobile apps/Netflix, etc. gigabit speeds in a single stream are not achievable.

This has also been brought up here: https://forums.xfinity.com/t5/Your-Home-Network/Gigabit-Service-only-providing-250mbps-down/td-p/3391986

@quindar7  That doesnt seem right. When I first received the service in March 2020 I was easily hitting 900+ down. Not just during speedtests, but steam downloads, etc... as well.

March 2020: https://imgur.com/X1FyEYG

January 2021: https://imgur.com/Ac5dVKF

Tech came out.

He replaced the drop line. Still slow.

He replaced the gateway. Still slow.

I played around with the coax coming into the house. Still slow.

He says the signal looks fine. He has no idea whats going out. Said he would need to have maitenance come out and look at the node. 

Also, it now looks like my speeds are dropping even lower on ethernet. I''ve gotten some speed tests around 150-160.

@mrthemike123 I never stated that this was always the case, but it appears to be more recent as I'm seeing a trend of new and supporting threads across the Xfinitiy Community Forum, Reddit, and my own tests. Additionally, your experience with techs coming out and needing to refer to another team (who will never show) has been the same for me. To that extent, could perform the following test to help the community?

1. Connect a 1Gbps capable physical or virtual device running Ubuntu directly to your cable modem (ensure it receives a public IP via DHCP, you may need to reboot your modem).

2. Install the Speedtest CLI

sudo apt-get install gnupg1 apt-transport-https dirmngr -y
export INSTALL_KEY=379CE192D401AB61
sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys $INSTALL_KEY
echo "deb https://ookla.bintray.com/debian generic main" | sudo tee  /etc/apt/sources.list.d/speedtest.list
sudo apt-get update
sudo apt-get install speedtest -y

3. Run speedtest from the CLI and report the results

   Speedtest by Ookla

     Server: Tachus Fiber Internet - The Woodlands, TX (id = 31012)
        ISP: Comcast Cable
    Latency:    19.96 ms   (4.06 ms jitter)
   Download:   940.06 Mbps (data used: 1.2 GB)
     Upload:    42.02 Mbps (data used: 45.9 MB)
Packet Loss:     0.0%
 Result URL: https://www.speedtest.net/result/c/45d34b63-2efc-4caf-be9f-b21ecfc51848

4. Install the Netflix Fast CLI

sudo apt-get install npm -y
sudo npm install --global fast-cli

5. Run fast -u from the CLI and report the results

     280 Mbps ↓ / 38 Mbps ↑

Since I tested on multiple machines I assumed it was NOT the ethernet adapter. However, they may actually all have the same incorrect settings.

I went back and changed a few settings based on a recommended online search and now i'm back up and running at 944down. Intel I225-V adapter.

For anyone that stumbles across this. Here is what I changed...Note, these settings may not work for your specific adapter. But the point here is that the adapter settings may actually be throttling your download speeds. 

• energy efficient ethernet: off
• interrupt moderation rate: low (THIS MADE A HUGE DIFFERENCE. it was set to extreme)
• ipv4 checksum offload: disabled
• large send offload v2 (ipv4): disabled
• large send offload v2 (ipv6): disabled
• receive buffers: 1024
• transmit buffers: 1024
• speed and duplex: 2.5 gbps full duplex

@quindar7 also thank you for your help

@mrthemike123 Thanks so much for taking the time to reach out to us regarding your slow speeds. I very much appreciate your patience and greatly apologize for the delay in our response. I know how important the services are to your home and we want to do all that we can to assist. I rely on my connection for everything, and I can imagine how frustrating it is to have slower speeds than what you are paying for. I would love to get to the bottom of the slow speed issues. Can you please reach out through private message with your first and last name, name on the account if different, and service address? If you’re having trouble locating this information, you can also reference our world-class MyAccount app to view all of your account details by the simple touch of your fingertips! Please follow the process here to learn how to obtain that information: https://comca.st/2LIGjyg;