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Only getting 400mbps on gigabit plan

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Frequent Visitor

Only getting 400mbps on gigabit plan

Back at the end of March I changed to the gigabit plan mostly to get the upload speeds for posting video files for our church services. I installed my own Netgear CM1100 bought from Costco. The upload speeds were fine and what I needed, about 42mbps, but from day 1 of the gigabit service, the download speed never got above 400, even connected directly to the modem. I spent time on the phone with both Comcast and Netgear tech support and finally replaced the modem last week with an Arris SB8200. It activated fine, but still only 400mbps. I managed to get Comcast to send a tech to my home. He confirmed that Comcast does not have the firmware to provision my Netgear CM1100 for gigabit, but said that the Arris SB8200 was properly provisioned with a "gigabit bootfile." He then managed to get a proper 930ish mbps download through my modem on his test apparaus. But I was unable to get any more than 400 on my, admittedly a few year old, Dell laptop directly connected by ethernet to the modem. The laptop has a gigabit network card with an ethernet port. And I still cannot get anything above 400 through wired connections to a Netgear gigabit router on two different, fairly new desktops with gigabit network cards. Please note that I am not at all talking about wifi speeds. This is all via ethernet. I am frustrated and simply cannot believe that the fault lies with my equipment. Any ideas?

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Regular Visitor

Re: Only getting 400mbps on gigabit plan

I didn't read in your post anything about cabling. Cat-5e? I would start replacing with Cat-7 or Cat-8 to remove any doubt. What brand/device did the tech use? Then find yourself a device that rocks GbE/2.5 and eliminate these segments one at a time.
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Regular Contributor

Re: Only getting 400mbps on gigabit plan

I seen a post where Dell loads software that limits download speeds, the poster removed the software and he got full download speeds, the program is called smartbyte

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Frequent Visitor

Re: Only getting 400mbps on gigabit plan

Thanks, but I tried the laptop I mentioned directly to the modem over the same short ethernet cable the tech used (the cable that came with the modem). So the cable does not account for the difference in what he got and what I got. I do not know what the tech's device was, some sort of tester box with an ethernet port, operated from a separate tablet, not a laptop.

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Frequent Visitor

Re: Only getting 400mbps on gigabit plan

I know about SmartByte and had eliminated that years ago. So that's not the problem either.

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Regular Visitor

Re: Only getting 400mbps on gigabit plan

Glad you weren't using dodgy cables. That rogue Dell app was interesting reading.
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Regular Contributor

Re: Only getting 400mbps on gigabit plan

Just a thought, did you check your gigabit network card settings? There are settings that determine speed etc, for example full or half duplex, makes a difference 

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Frequent Visitor

Re: Only getting 400mbps on gigabit plan

O.K., I'll update and try to set the record straight, in some fairness to Comcast. As I said, I had been testing speed direct to the modem with a laptop containing a gigabit network connection. I still do not know why that laptop cannot do more than 400mbps. However, yesterday I decided to try and connect a desktop machine we have direct to modem (had to run a 25 foot cat 5e cable down the hall) rather than through our router. I was pleasantly surprised when the desktop got high 700s, instead of the 400 it was getting through our router and wired network. Since all the cabling in our network is cat 5e, I am not suspecting cables at this point but instead our Netgear N600 WNDR3700 router which is supposedly gigabit. But a little research suggests that it does not actually do full gigabit throughput. I've ordered a Ubiquiti Edgerouter 4 (we weren't using the wifi in the Netgear router anyway) and will see if that helps bring speeds up for the desktops on our wired network. There is evidently nothing like a simple consumer-oriented wired-only router to be had, but I'm hopeful I can get the Ubiquiti up and running using their setup wizard and looking for tutorials if I get stuck. Actually getting the speed I'm paying Comcast for is turning out more costly than I thought it would be.

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Frequent Visitor

Re: Only getting 400mbps on gigabit plan

One last update if anyone is following this thread. The Ubiquiti router was a success. I recommend it to anyone as a solution for use with Comcast gigabit service. I also discovered that, while the Comcast speed test run in a browser consistently gets speeds around 600-700 and speedtest.net in a browser typically gets into the 700s, the speedtest.net standalone app regularly shows speeds in the 900s, which is what one would expect with gigabit service. I'm not sure what the browser slow down is. I've tried both Firefox and Chrome and I'm running Norton 360 pretty barebones (no browser extensions enabled). But seeing that dial wind up to 900 in the Speedtest app makes me feel gratified for the effort I've put into resolving this. I do wish Comcast had technical people who would be capable of and willing to offer better guidance for resolving such issues with customer systems, but I get their mentality that if they can show the right results coming out of the modem, the rest is the customer's problem. Oh well, such is our world.