AT&T Fiber vs. Comcast Business Class internet service

Last Updated: Oct 06, 2020

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I have been a mostly satisfied Comcast Business Class customer for many years. But recently, AT&T GigaPower, the company’s superfast, fiber optics internet service came to our neighborhood in Alpharetta. I had the opportunity to try it out and compare it to Comcast Business Class.

To better understand the differences in service, I will also give you a high-level overview of the technologies used by Comcast, AT&T and other Internet Service Providers (ISPs). That’s important because the underlying technology often affects reliability and speed.

The need for speed and reliable service

I work from home and fast, and reliable internet service is crucial for my job. That’s why I switched from Comcast’s residential to the company’s business class service a few years ago.

Fiber optic cable
Fiber optic cable

With most residential service offerings, you share the internet connection with other customers who live in the same apartment complex or street. As a result, you may only get a fraction of the speed your connection supports. With Comcast’s Business Class service, I had a dedicated line that I didn’t have to share with anyone else. Plus, customer care is usually better when you are a business customer.

The Comcast service I had offered a maximum download speed of 100 megabits per second (Mbit/sec) and a maximum upload speed of 20 Mbit/sec.

Despite the relatively fast download and upload speeds Comcast offered, I needed more. The number of devices on my network is continuously growing, thanks to IoT (Internet of Things) devices, such as thermostats, room monitors, light switches, etc. Additionally, I store more and more data in the cloud, including backups, photos, documents, etc. That continuous transfer of data means that my internet connection is never idle. That’s especially critical with data uploads, such as backups, because a congested upstream can cripple your entire internet connection.

That’s why I got excited when I heard that both Comcast and AT&T are building out their fiber optic services in the Atlanta area. Google was the first to offer residential gigabit Internet in the Atlanta area, but they never made it to northern metro cities, such as Alpharetta.

Network technology used by ISPs

Most ISPs in the United States offer their residential internet services using coaxial (coax) cables or Digital Subscriber Line (DSL) technology. With both, you often get an internet connection that offers much faster download- than upload speeds. That’s called an asymmetric connection, and it is what I had with Comcast.

Different cable technologies
Various cable technologies: Ethernet, Coaxial, Fiber Optic

Comcast Business Class service

Comcast uses coax cables for most of their consumer-facing network infrastructure. That’s the same old technology that cable companies use for TV service. The problem with coax cables is that they are prone to electromagnetic interference (also called noise). The same is true with most other non-optical cables, and it can result in degraded service. Also, the longer the coax cable is, the weaker the signal is due to resistance. So-called splitters that split up the signal to feed your TV and internet modem can further reduce signal strength.

AT&T GigaPower vs. Comcast Business Class internet service
Comcast Business Class 100

The Comcast service at my house has been relatively reliable over the past few years. But I did have issues with “noise” on the line that resulted in degraded service. So I had a Comcast technician out a few times to replace the modem, the splitters and even the cable that connects my house to the junction box at the street.

Lately, I experienced more frequent connection problems than I had in the past. Those issues affected mostly my upload speed, or so-called upstream. Instead of the 20 Mbit/sec, I would only get 3-10 Mbit/sec. The first time I called Comcast about that issue, the technician told me that the problem was related to network infrastructure on Comcast’s side. The issue was ultimately resolved but returned shortly after. The second time around, Comcast blamed the problem on my networking equipment because they couldn’t find an issue on their end. That motivated me to look for fiber optic-based solutions that aren’t prone to those problems.

Comcast’s fiber optic internet service

The last technician who came to my house told me about Comcast’s fiber-optic service that should come to our neighborhood sooner or later. He said that Comcast had a vast coax cable infrastructure that would be expensive to replace with fiber optic cables. So Comcast started working with a company that could remove the copper conductor from old coax cables and replaces it with a fiber optic link.

Unfortunately, Comcast decided to still use coax for the link between the customer’s modem and the junction box on the street. As a result, you still have a weak coax connection that is susceptible to noise and can lead to service degradation. In other words, you may still end up with an unreliable, asymmetric internet connection that’s not much more reliable than regular cable service.

AT&T GigaPower vs. Comcast Business Class internet service
AT&T GigaPower Internet 1000

AT&T GigaPower to the rescue

Unhappy with Comcast and their outdated technology, I took a closer look at AT&T’s GigaPower service. On their web page, AT&T promises download speeds of up to a 940 Mbits/sec. Before jumping in head first, I wanted to get the following questions answered:

  • What’s the upload speed?
  • Is the link symmetric or asymmetric?
  • Do I have to share my bandwidth with anyone?
  • Does the fiber optic cable go all the way into the house?
  • What equipment is used to convert the fiber optics link to Ethernet?

The good news is, AT&T seemed to have made the right technological choices for consumers, at least in my area. The GigaPower service delivers upload and downloads speeds of up to 940 Mbits/sec. The fiber optic cable goes all the way into the house and gets converted to Ethernet by a so-called Optical Network Terminal (ONT). As a result, there is no coax used at all, which dramatically increases the reliability of the service. Fiber optic links are not susceptible to interference, and you can use cables that are much longer than coax or ethernet cables.


I ordered AT&T GigaPower on a Thursday, and two days later, on Saturday, the installer came out to install the service. It took approximately two hours to assess my location, and run the fiber optic link into my house. About a week after the installation, another crew came out to bury the cable.

Where the cable entered the house, AT&T installed an ONT on the inside of the wall. The ONT converts the signal to Ethernet before it reaches the Arris BGW210-700 router.

AT&T GigaPower vs. Comcast Business Class internet service


With Comcast, I had a static IP that I assigned to my AmpliFi wireless router while I had the Comcast modem set to “bridge mode.” As a result, the Comcast modem would pass through all traffic to AmpliFi, which took care of DHCP, WLAN, and routing.

I don’t need the static IP for operating a server, but I want to be able to monitor the status of my internet connection via Uptime Robot. AT&T sells static IPs in blocks of eight for $15 per month, which is reasonable.

Unlike the Comcast modem, the Aris BGW210-700 doesn’t support bridge mode, and it requires some extra steps to simulate it. Unfortunately, I wasn’t at home during the installation, so I had to do the configuration after the technician had already left.

How to enable bridge mode

Unlike other users, my goal was to assign one static IP address to my AmpliFi wireless router so that I could ping it from the outside. I had no intention of assigning additional static IPs to devices behind the AmpliFi router, and I also did not want to just pass through the dynamic IP of the Aris modem. Additionally, I wanted to avoid double Network Address Translation (NAT). With that in mind, here are the steps I took to configure the Aris modem:

  • Disable Wi-Fi
  • Disable IPv6
  • Enable Public Subnet
  • Set Primary DHCP Pool to Public
  • Allocate one public IP to MAC Address of AmpliFi router

The first thing I did was to disable both 2.4 and 5Ghz WiFi networks under Home Network –> Wi-Fi. Make sure you select both radios and turn them off! Next, I configured my static IP subnet under Home Network –> Subnets & DHCP and changed the DHCP Pool to Public. In my case, AT&T assigned the following subnet to me: 108.xxx.xxx.230/ In other words, I have five usable addresses:

  • Network address: 108.xxx.xxx.224
  • Usable range: 108.xxx.xxx.225-229
  • Gateway: 108.xxx.xxx.230
  • Broadcast: 108.xxx.xxx.231

Next, I allocated the first usable static IP address (.225) to the AmpliFi router via it’s Media Access Control (MAC) address. Of course, I enabled DHCP on the AmpliFI router instead of using a static IP.

If your goal is to pass through the dynamic IP address to a router behind the Aris modem, check out this post. If your goal is to assign your static IP addresses to devices behind your wireless router, check out this post instead.

Speed test and buffer bloat
Speed test and buffer bloat

Speed test and real-life performance

For it’s Internet 1000 (GigaPower) service, AT&T promises speeds between 500 – 940 Mbps when you measure directly from the ethernet port of the Aris modem. I am more interested in test scenarios that reflect my network infrastructure and all its connected devices.

Additionally, I wanted to see how well the service performs under load. In other words, how much latency increases when the connection is congested. Networking professionals call that “buffer bloat, ” and my Comcast connection scored badly in that area. I have performed all speed tests from my iMac that I connected via an optical Thunderbolt cable to a LaCie 5big RAID. The storage device in daisy-chained via a Thunderbolt-to-ethernet adapter to my AmpliFi wireless router. Here are the results:

  • Download speed: 480 – 660 Mbps
  • Upload speed: 510 – 590 Mbps
  • Latency: 4 ms
  • Buffer bloat rating: A

In comparison, my the results from my Comcast services look different:

  • Download speed: 118 Mbps
  • Upload speed: 8 Mbps
  • Latency: 11 ms
  • Buffer bloat rating: D

Regardless of the up- and download speed, you can see that the fiber optic-based service offers half the latency and almost no buffer bloat. That means that under load the latency only increases minimally. You can learn more about buffer bloat here.

AT&T GigaPower vs. Comcast Business Class

Comparing AT&T’s GigaPower service with Comcast’s cable service is like comparing apples to oranges. At least from a pure speed perspective. However, it’s important to note that AT&T charges $80 per month for its Internet 1000 service, while Comcast Business Class 100/20 costs $149.95 per month. Comcast’s residential 100 Mbps service costs $84.95.

So with AT&T, you get a faster and more reliable service that is based on 100% fiber optics for less money than what Comcast charges for its coax-based service. As a result, AT&T’s fiber optic service is the clear winner, and I am glad I made the switch. What’s your experience with AT&T’s new service? Let me know by leaving a comment below!

22 thoughts on “AT&T Fiber vs. Comcast Business Class internet service”

  1. Add the site UptimeControl.net to the article, because only they have a 3-minute site availability check interval on the free plan.

  2. Hi Michael, this is an awesome article, I just switch from Comcast to Att fiber 1000. Because I have wireless and Directv now it will only cost me $60 a month. I live on SW Atlanta in the Cascade neighborhood and fiber just became available. I’m getting 174/9 on a good day and sometime it’s as low as 5mbps so I’m excited to see what fiber has to offer. I have about 30 devices and it’s getting rough streaming. Well thanks again for the great article and advice

  3. An east Cobber (Marietta GA) here as well. I see the digging has finally been completed in my neighborhood. Can’t wait to jump up to this. Regardless of price, it will be lightyears ahead of anything DSL.

  4. Anyone had problems with BGW210 port forwarding or IP passthrough functions? I don’t have fiber yet, but recently upgraded ADSL service and ATT installed this gateway. However it won’t forward ports even though the correct applications can be set in the NAT/Gaming tab.

  5. To respond to Kenneth James Grater’s question:
    An AT&T FTTH multimode optical fiber terminates at an ONT device, usually wall-mounted indoors in your garage, utility room or attic. The ONT acts like a modem, converting between an optical signal and an electrical Gigabit Ethernet signal on CAT5e UTP cable. The ONT also acts as an intelligent remote node of the AT&T fiber-optic network, with extensive diagnostic capabilities. The other end of the CAT5e UTP cable is connected to the red ONT WAN port on the Arris BGW210-700 Broadband Gateway (or other AT&T Gateway). If you have AT&T DSL service instead of FTTH, you connect your AT&T service cable to the green BROADBAND WAN port. Either way, the Broadband Gateway supports the necessary protocols to connect and communicate with the AT&T network (obviously different for Gigabit FTTH and DSL), but not with the DOCSIS 3.x protocols used by the US cable companies.
    Here’s a link to the Arris BGW210-700 Broadband Gateway User Manual (it’s fairly basic but has some useful specs):

  6. As another metro Atlanta AT&T customer with Gigabit residential:
    – Arris markets the BGW210-700 as a Broadband Gateway, it is far more than just a router, and is “bundled” with the service
    – The current AT&T ONT for indoor FTTH installations is a version of the Alcatel-Lucent G-010G-A. The field techs call them demarcs, ONTs, NIDs, modems and many other names (often technically misleading or incorrect) etc etc. Note that this ONT is mounted in a protective bracket with a matching lower cover (removed in your photo) that hides the power/cable/fiber jacks and the RESET button from us pesky customers.
    – It’s noteworthy that AT&T has opted to forego an integrated ONT backup battery power source. CLECs have been plagued with alarms, failures and customer complaints caused by FTTH ONT battery failures, and VoIP telephone service requires additional downstream equipment to have power anyways, so customers are left to make their own residence-wide plans for power outage situations and emergency preparations. I’m told that new homes only get VoIP “landlines” from AT&T, POTS is being systematically phased out and we’re all learning to rely on cellular service and satellite during power outages.
    I’d be interested to hear from anyone who’s experimented with connecting their own (higher-performance) Wi-Fi router to the AT&T/Arris Gateway instead of using it’s impressive internal Wi-Fi.

  7. To Peter P. The box on the outside of the house is called a slack nid (Network Interface Device) and serves as a demarc for the drop running to the home so they can use a fiber jumper inside to the ONT and can detach the drop from the home in the event it needs to be replaced.

  8. Great article. I have the same situation in east Cobb. I didn’t get a range of addresses from AT&T. Maybe my address is static. I really forgot to ask. The dynamic addressing from Comcast seem to rarely get changed. I have been trying to “cascade” my Arris and use my Asus RT router. AT&T finally booted and said they’d send my another BGW210 with current firmware. Not sure what is going on. I may try your setup.

  9. why wouldn’t the techs run the fiber all the way up to the BGW1`0-700 modem? Or is the ONT connector on the modem really not a fiber connection?

  10. Michael,

    You mentioned:
    Where the cable entered the house, AT&T installed an ONT on both sides of the wall. From there, the ONT on the inside converts the signal to Ethernet before it reaches the Arris BGW210-700 router.

    What doe the one on the outside do? Why two?

    • Hi Peter,

      I took a peek the other day, and the outside terminal is actually not a terminal at all. It’s just an empty box that covers the hole in the wall they drilled. All the magic happens on the inside terminal.

  11. Thank you so much, I spoke with At&T about the Small Business plan, I have an Office with 6 computer and about 5 Voip phones running at one time. I am sick of Comcast. Out of contract, time for a change.

  12. Thanks for your blog and post. Just installed AT&T’s residential fiber gigapower service here in north MS about a week ago to replace a much slower Comcast cable internet service. Not really much to consider when comparing a 1000/1000 megabit fiber connection to a 12/3 megabit copper connection, with only a $20/month price increase ($70/month vs. $50/month). Installation was smooth, service is about as quick as advertised, and there have been no drops in service since we went live. All that said, I am not a fan of the Pace 5268ac wifi modem/router provided by AT&T. No true bridge mode exists on that device so I had to turn off the wifi radios and use the DMZ+ feature in order to plumb and keep our existing Asus AC88 wifi router as the nominal network head-in for our entire wired/wifi internal network. Seems to be working well so far and we are enjoying the tremendous increase in internet speed.

  13. I live in East Cobb. AT&T lit our neighborhood July-Aug 2017.
    A sales agent visited my house in September, so I placed the order to switch from Comcast. AT&T failed to install my order with 3 technician visits. Each time the tech said the demarc was not lit. I let the order die and reported it to our subdivision liason for the fiber project. I will try again after the holidays.

  14. Great post. AT&T rolled through our ‘hood over in East Cobb and I just got a flyer that it’s now ready. I’ve been a rock-solid Comcast Biz customer for about 5 years, but I need more bandwidth! MOAR BANDWIDTH!

  15. We still don’t have AT&T fiber in our neighborhood in Gwinnett. I’m paying $40 for my 24Mbit Uverse Internet. I upgraded to 50Mbit Internet, and AT&T they give me twice discount to lower my monthly to $30/month. That’s 2 DSL lines multiplexed to give me real life 43Mbps DL and around 11Mbps UL.

  16. Michael, thanks for the excellent overview. I also live in Alpharetta, work from home and use Comcast Business Class service.

    It looks like it is time for me to call ATT!

    Thanks again,



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