Arris (S33-RB) - Cable Modem - DOCSIS 3.1 Multi-Gigabit Cable Modem for Comcast Xfinity, Cox, Spectrum & More 1 & 2.5 Gbps Ports 2.5 Gbps Max Internet Speeds 4 OFDM Channels 1 Year Warranty - Renewed

Works perfectly with Comcast/Xfinity. Super easy to setup, good quality at a good price. Provides a much higher speed than older units.

I have nothing to complaint about the modem itself. It is a factory refurbished model and looks like new. Installation on Xfinity was smooth, just had to remove my old Motorola plug the coaxial and Ethernet cable to the S33, plug it to the wall outlet, open the Xfinity app and add the new modem. It worked on the first try. I have the 1.2gb/s plan so I’m supposed to get 1.2gb/s download and 120mb/s upload. As I’m limited to my router’s 1gb/s port I’m not expecting to get 1.2gb/s download but the 120mb/s download would be very welcome. As you guys can see in my second picture I’m getting about 977mb/s download and 948mb/s upload internally using a gigabit LAN connection. The third picture shows a internet test and there is where the problem using the S33 with Xfinity is, can’t get 120mb/s upload because Comcast blocks this modem from using mid-split with their network because they say it has not been certified so if you want that fast upload speed you will have two options, renting their modem or buying a Hitron CODA. I’m giving the product 5 stars because it’s pretty good and the issue with Xfinity is not the product’s fault so if you don’t rely on high upload speeds using Xfinity go for it, it’s certified by Xfinity for up to 2.33gb/s download but if you need high upload speeds look elsewhere.

For a point of reference, I'm a network engineer. This is easy to set up, if it works for your specific application. The problem with it is, there is no way to easily configure things such as the internal DHCP server or certain security features you'd have access to with an older modem. If your firewall on your network will not receive a DHCP address correctly from this device, you have little options for resolving the issue. I wiresharked the connection and my firewall was failing to negotiate an IP lease from the modem. With no way to access any meaningful interface other than the web interface on the modem (which is useless since it only shows information and does not allow any configurations to be edited) or using the completely worthless Arris android app, which is just informational and does nothing to configure the device, you're screwed. I've had the device randomly fail several times. Each time the DHCP server in the device failed to hand out an IP address to my firewall. One time, the cable company pushed out a firmware upgrade which broke it. The firmware upgrades have also removed my passwords and reset them to the default. Bring back user editable configurations and my rating would go up. But this canned one size fits all unconfigurable crap is a pain in the butt.

ARRIS Surfboard S33-RB DOCSIS 3.1 Multi-Gigabit Cable Modem (Renewed). I've had an Xfinity DOCSIS 3.1 rental modem/router combo for several years rent free. That deal came to an end so I purchased a renewed version of the ARRIS Surfboard S33 to avoid the $14.00/month rental fee.The rental modem/router worked great with consistent 940 Mbs download speeds and 40 Mbs upload speeds without a VPN connection and about 700Mbs download speeds with a VPN. I generally use a VPN so I wanted to purchase a DOCSIS 3.1 modem that was at least as fast as the Xfinity rental modem. The ARRIS S33 provides nearly identical upload and download speeds as compared to the Xfinity rental modem.I had an ASUS RT-AC1900 dual band gigabit router in storage to add to the ARRIS Surfboard S33 modem.The ASUS router is an older 802.11ac router but it's performance exceeds the router built into the Xfinity modem/router combo. I was not looking forward to calling Xfinity on the phone to activate my new/refurbished ARRIS Surfboard S33 modem so I opted to use the Xfinity app on my phone to complete the activation.I don't have a great cellphone signal in my rural house and of course no in-home WiFi at this point in the modem activation process so I walked down the road until my reception improved and typed the 12 digit MAC address into the Xfinity app and hit send.Much to my delight,when I got back to the house five minutes later the blue light was lit on the S33 and I had a nice speedy internet connection. So far so good with my refurbished modem. I've generally had good luck with my electronics gear new or used. Hopefully my luck holds with this renewed ARRIS S33 modem.