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Testing T25 Modem

  • December 5, 2025
  • 1 reply
  • 11 views

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What I sent Arris tech support…

I recently (December 4, 2025) replaced an Arris T25 modem with an Arris S33 modem.  I like Arris products.

 

The T25 gave me over 6 years of continuous, uninterrupted 24/7 service and saved me a boat load of money owning my own modem instead of renting one from my ISP (Xfinity).  ( Replaced an older Arris slow speed modem with the faster speed T25).  The internet indicates typical useful life of modems between 5 and 8  years.

 

The T25 all of a sudden stopped working on December 1, 2025.  The power light dimly lit but the modem would not accept or transmit data and the internet was down.  I confirmed proper power was fed to the modem (12 volt from the adapter) and that the ISP was providing a proper signal.  I did all the usual reboot and troubleshooting effort with no results.  The new S33 modem installed without a hitch and now my internet system is functioning back to normal again – so as I suspected a busted T25 modem.  During a 24 hour outage, I used my iPhone as a hotspot modem and also used the internet from a neighbor, so home office needs continued without delay.  [I learned about hotspot internet backup with my iPhone as  part of emergency backup plans, especially if power outage – can use phone battery power].  As an aside, all our sensitive electronic equipment, including the modem, are connected to surge protectors and emergency battery backup units.

 

At any rate, I am quite curious why the T25 stopped working. 

 

I am happy to ship the T25 at my expense to Arris designated technical site in exchange for Arris to give me a report of the testing and investigation of the modem as to what the failure cause was.  As an engineer, I am curious, and I suspect Arris would be equally interested in understanding a possible preventable failure by testing and analyzing the T25.

 

Let me know if interested and if so a shipping address and any other instructions.

 

Thx

 

 

 

1 reply

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We apologize for the inconvenience, but unfortunately we don’t offer a service where you can send the modem to a tech site for diagnosis. However, you can still check the modem on your end by verifying whether the device has been assigned an IP address.

To check the Ethernet port status, you can connect the modem directly to a computer and check the IP address without the coaxial cable connected.

To check the IP address on a Windows computer, please follow these steps:

  1. Press the Windows button + the letter R on your keyboard to open the "Run" command box.
  2. In the box, type "CMD" and press Enter.
  3. A black screen will appear. Type "ipconfig" and press Enter.
  4. Under the category 'Ethernet adapter Ethernet,' you’ll find the IPv4 address.

To check the IP address on a Mac:

  1. Click on the Apple menu.
  2. Then, select System Preferences or System Settings.
  3. Navigate to Networks and click on the Ethernet option to view the IP address.
  4. If you're using an adapter, you’ll see an option for USB under Networks.

If the IP address starts with 169.254.., or if the media state shows 'disconnected' or the category is blank, there could be an issue with the port itself.