Arris (T25-RB) - Cable Modem - Fast DOCSIS 3.1 Gigabit Cable Modem, Comcast Xfinity Internet & Voice, Two 1 Gbps Ports, 800 Mbps Max with Xfinity Plan - Renewed

I installed the Arris T25 modem about a week ago. It replaced an Arris Surfboard 6190. I bought the T25 to use Xfinity Voice which is part of my plan but which I never used. The modem has been operating since installation without any incidents. Internet download speeds went from 600Mbps to 900Mbps. The telephone line has performed perfectly.Installation was not as straightforward as I would have liked. Since I don't have an exceptionally strong cellular signal where I live I first tried connecting a laptop directly to the modem and using the Xfinity activate webpage from a browser. I got nowhere trying that. I always ended up back on a webpage that told me to download and use the Xfinity app on my smartphone. Despite the weak cell signal I decided to try the Xfinity app from my phone. Scroll down in the app to where it says, "Got new equipment to set up? Activate now." It worked fine. The app only asks for the modem's HFC MAC ID, not the MTA MAC ID. After a few minutes of watching the lights on the modem cycling the app reported that the modem was online and provided the telephone number assigned to it. That was it - internet working, telephone working, no call to Comcast required. I connected my Asus router to the modem and I was good to go.Update: A frequently asked question is whether the modem can be connected to extension phones in the home. The answer is yes. However, my first try wasn't successful. I connected the modem to a wall jack that's connected to all of the extension phones after first disconnecting the phones from my current landline supplier at their demarcation box. The phone light on the modem started blinking as if the line was in use, but it wasn't. The displays on my extension phones also showed "Line in Use." I disconnected the modem from the phone jack to think about what the issue could be. A few days later I tried again but this time thought to disconnect a printer/fax from its phone wall jack. All of the extension phones now worked perfectly. I'm not sure why the printer/fax would cause a conflict when it was not in use, but all of the extension phones are working fine now. I can live without the fax if I have to.Update March 14, 2024: I think it's helpful to update reviews after a product has been in use for some time. I've been using this modem for internet and phone since November of 2022, and its performance has remained absolutely solid. I have not had to reboot it once. Very happy.

I decided to purchase my the Surfboard telephony enabled modem (T25) along with a tp-link ax3000 wifi router for my Xfinity superfast plan (800Mbps/20Mbps). I figure in 2 years it will cover the 15/monthly rental. Installation for both was simple and straightforward and I didn't need to call up Xfinity. Afterwards my connection and wifi signal were about the same or slightly better than I had before. The app for setup was about as easy as I feel they could make it. Following are notes from install process:- optional: perform speed test on your phone and laptop in various areas of home noting strength of signal (for comparing with new modem setup at end of the process)- download apps ahead of time and setup accounts (if needed) ahead of time - modem (surfboard central for surfboard modem) - router (tether for tp-link) - xfinity app- open the surfboard central app and start the wizard to add the modem - select "ISP cable connected without wifi" and "t25" - this starts a wizard guiding following steps- connect the surfboard modem and disconnect the xfinity gateway- in the XFinity app search for "activate new modem" and activate - enter the HMAC (HFC) manually (could not find a QR code to scan) - you never need to enter the telephony HMAC (MTA)- wait several minutes for the modem to activate with XFinity - shows "checking connections" for a few min - shows "finishing" for a few min - test landline phone (may take a few minutes longer)- shut down modem and connect wifi router to modem- start modem then router - wait a few minutes for internet light on router to show up- connect your mobile phone to wife using QR code at bottom of router - initially wifi connection on phone shows connected without internet- go to wifi router app (tether for tp-link) and configure wifi network - scan QR code to add - update ssid and password- now internet should show up on your mobile phone connected to the wifi- uninstall surfboard central app -- only needed for wizard

We purchased this modem specifically because it's certified by Comcast for its gigabit Xfinity internet service. It also incorporates an eMTA (telephone adapter) for the Comcast VoIP / landline service.Installing it was easy and simple enough; however, getting Comcast to properly provision it took several days and numerous provisioning hits and power cycles.Comcast says it cannot see the anything inside the modem including the signal levels, signal-to-noise ratios or anything behind the password protected advanced page.The modem has slow upload speeds and will reboot itself almost every night. This knock everything in the house off line and makes cloud backups frequently crash. The modem reboots do not correct the bad internet service.There are plenty of similar documented problems on Comcast's support forums and elsewhere.We had no problems with an older gigabit modem and a separate eMTA, but nothing but problems with this Arris T25 modem.I see plenty of these being sold at the Amazon warehouse at discounted prices, and now I understand why.Arris tells us that the upload signal levels are out of spec. Comcast says everything is OK. I tend to agree with Arris, based on the error logs, frequent reboots, and uploads hanging.Very frustrating to have a Comcast certify and recommend this modem, but not be able to see what's going internally. And then to blame the vendor they recommend.Whatever Comcast may recommend -- I DO NOT recommend this Arris product as there is no way to determine if defective chips are present or not and no way to get a reliable, stable, internet connection."Lost MDD Timeout" error message causes the reboot -- every day at 23:30 or so.