Visitor
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1 Message
Gigabit x2 slow speeds
I just got Gigabit X2 package with 2100mbps down and 300 mbps up. I have a brand new ARRIS G18 modem with CAT8 Ethernet cable. I get 944 mbps download speeds and 40 mbps upload. My laptop is less than a year old with Gigabit Ethernet. I have had technical support re configure my modem many of times over the phone. Re provision at least 4 times so far.
EG
Expert
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110.5K Messages
7 days ago
That modem is not compatible with their new Next Gen / mid-split /enhanced upload speeds. These are the only third-party / retail purchased devices that are currently compatible;
As are their XB6, XB7, and XB8 rented gateway devices.
Also. you will not get any faster than around 940-950 Mbps down, as it only has gigabit ethernet ports.
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BruceW
Gold Problem Solver
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26.4K Messages
7 days ago
The G18 is not compatible with Gigabit X2 internet service or with the higher upload speeds introduced in 2023. Comcast/Xfinity rates it for use with plan speeds "Up to 934 Mbps". See the link to the "All Compatible Devices" PDF near the bottom of https://www.xfinity.com/support/devices (at the moment it points to https://assets.xfinity.com/assets/dotcom/projects/cix-4997_compatible-devices/2025.03.25 Full List of Compatible Devices.pdf, but this changes from time to time).
Please be aware that there are 2 kinds of responses in this Forum: Replies and Comments. When you Comment on a post by scrolling down to "Comment on this post here...", I am notified of your response. But if you select Reply, I am NOT notified and may not be aware of your response.
(edited)
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XfinityJustinC
Official Employee
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1.3K Messages
5 days ago
Hello, @user_a46a52 thank you for taking time to reach out over Xfinity Forums. Working from home myself, I completely understand wanting to get the most out of your home network. I appreciate the information with the modem you're using, and want to help with the speed concerns.
Reviewing our certified modem list: https://assets.xfinity.com/assets/dotcom/projects/cix-4997_compatible-devices/2025.03.25%20Full%20List%20of%20Compatible%20Devices.pdf
The G18 is not able to support speeds over 1 gigabit download and not supported for higher upload speeds above the 35/40 MBPS range on our network. To get the full capabilities of your speed, you would want a mode off the Next Gen Speed Tier list on the above article that can support up 2.33 GPBS and the higher upload speeds.
Please let me know if that was helpful, or if you have any further questions.
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