The T25 modem has never been launched with DOCSIS 3.0. The model released in 2019 supports DOCSIS 3.1 only.
Please double-check the configuration settings. Even though the T25 is DOCSIS 3.1 compatible, it’s possible that your Internet Service Provider (ISP) is not transmitting DOCSIS 3.1 signals.
According to Xfinity, the T25 is approved for speeds up to 949 Mbps, which is why it’s often labeled as “Best for internet plans with up to 800 Mbps.”
You can refer to the link below for details on speed plan compatibility under Xfinity.
https://assets.xfinity.com/assets/dotcom/projects/cix-4997_compatible-devices/2025.03.25%20Full%20List%20of%20Compatible%20Devices.pdf
Also, the modem has two Ethernet ports on the back, each supporting speeds up to 1 Gbps.
The T25 is a standalone cable modem and does not include a built-in DHCP server. As a result, when your internet service provider (ISP) activates the modem, it typically assigns only one public IP address, which supports a single internet connection.
If you wish to use both Ethernet ports on the T25 simultaneously, you would need to contact your ISP and request the activation of a second public IP address. However, please note that not all ISPs offer multiple public IP addresses for residential customers.
Therefore, if both Ethernet ports on the modem are activated, you can use them simultaneously. Each port supports speeds up to 1 Gbps, allowing for a combined throughput of up to 2 Gbps.
Please refer to the link below for more information on how Ethernet ports function.
https://arris.my.salesforce-sites.com/consumers/articles/knowledge/T25-Ethernet-Ports
