Slow download speed on WiFi - Netgear C6900 Cable Modem Router

[Eliasz]

Hi , I'm posting the issue here as a last try before I return the device to Costco.

I got Netgear C6900 cable modem router as a replacement of a reneted xfinity gateway.

My internet plan is upto 400Mbps and I used to get internet speed on the xfinity gateway wifi above 360Mbps while I got a disappointment speed on the newly high speed Netgear C6900 gateway around 266Mbps on 5G and around 80Mbps on 2G using speedtest.net and xfinity speed test on my laptop, galaxy note 9 and iphone, if I'm lucky. I wired my laptop into the gateway and got download speed above 400Mbps.

Here are some other steps I've done:

1- Contacted xfinity Support to complain about the speed sloweness issue, after troublshooting the issue they said nothing can do from their end and recommended to contact Netgear Support.

2- I contacted Netgear Tech. Support, opened a ticket, and did all the fixes that they recommend (changed channelsfrequency, the 24 Downstream Bonded Channels are all locked, device restart and gateway hard reset) and that didn't help. In the end told me I should wait about 48 hours and contact them again if didn't get resolved.

3- After 55 hours I contacted Netgear support again and went over the troubleshoot steps once more and that didn't help as well, then siad I need to contact xfinity Support to do a firmware re-provison.

4- I contacted xfinity support and asked them to do firmware re-provision and that didn't help also.

Any advice on fixing this issue would be great.

[plemans]

If you're getting 400mbps hardwired into the C6900, then its not an xfinity issue as they're providing full speeds to the modem. 

It could be a device limitation. The C6900 is an all in one unit, its not going to have the same performance as a single router solution because it has to run a modem along with the router. 

What xfinity gateway did you have?

its tough to compare without knowing which model you had for the same reason comparing the C6900 to the CAX80 isn't comparing apples to apples. 

What device are you testing on?

what website are you testing on? 

[Eliasz]

It could be a device limitation -> Not sure about that but the device should deliver upto 1300Mbps on 5G and 600 on 2.4G

What xfinity gateway did you have? -> XB7-T (pictures attached)

its tough to compare without knowing which model... -> I agree but the Netgear device technical specifications says this modem router should be good enough to deliver the 400Mbps download speed.

What device are you testing on? -> HP Pavilion Laptop (new model) with Intel® Wi-Fi 6 AX 201 (2x2)(19e) (Supporting Gigabit file transfer speeds), Samsung Note 9 & iPhone 7

what website are you testing on? -> www.speedtest.net, speedtest.xfinity.com and other websites that are available on google search

[plemans]

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@Eliasz wrote:

It could be a device limitation -> Not sure about that but the device should deliver upto 1300Mbps on 5G and 600 on 2.4G-----If only that was true. You're lucky if you hit 60mbps over 2.4ghz. And the performance of 5ghz is very router and device dependant. For example, the router hits 1300mbps by using 3x3 anteanns at 433mbps. Most wireless devices are only 1x1 or 2x2 antenna setups. So their max connection is 866mbps. And thats link speed. LInk speed is NOT throughput speed. You can read a lot more about it here: Understand Wi-Fi 4/5/6/6E (802.11 n/ac/ax) (duckware.com)

What xfinity gateway did you have? -> XB7-T (pictures attached)---The XB7 is literally comcast's top of the line device. Its a AX router with capability of hitting 2.5gbs wired versus the C6900 is an AC router. Its certainly not an apples to apples comparison. 

its tough to compare without knowing which model... -> I agree but the Netgear device technical specifications says this modem router should be good enough to deliver the 400Mbps download speed.----See the prior responses. it does hit that wired from what you're saying. You won't hit 400mbps over wireless with the C6900. 

What device are you testing on? -> HP Pavilion Laptop (new model) with Intel® Wi-Fi 6 AX 201 (2x2)(19e) (Supporting Gigabit file transfer speeds), Samsung Note 9 & iPhone 7----So you're comparing an AX router in the XB7 testing on an AX chipset  to an AC router. Of course your speeds will be less. If you want to compare testing on AX, buy the RAX120 or RAX200 for a similar comparision. 

what website are you testing on? -> www.speedtest.net, speedtest.xfinity.com and other websites the available on google search

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[Eliasz]

@plemans thank you for your replies!

I'm not an expert with modems and routers networks but previously I had a NETGEAR Nighthawk AC1900 WiFi Router (R7000) (purchased 5 years ago) wired into the xfinity XB7 gateway and the minimum download speed that I was getting was around 350Mbps on 5Ghz. However, I've just wired the same R7000 into C6900 and I got around 315Mbps speed on 5Ghz which is abviously more than the download speed on C6900 router 5Ghz wifi.

So, my conclusion here is this device's router is a joke and I'm going to return it and get a dedicated modem and the latest wifi 6 router or a mesh wifi system, instead.

[plemans]

the R7000 is indeed more capable in terms of wireless than the R6900.

You'll see more performance using seperate devices versus buying an all in one. Again, an all in one has to share resources (both cpu, ram, and even the power budget its allowed) between the modem side and the router side. 

I wouldn't call it a joke just because you didn't understand the difference. Its more of a misunderstanding. 

I'd highly recommend buying the modem seperate. ISP's control firmware on combo devices versus stand alone routers, you control the firmware. So besides that, the performance difference, and even the fact that you can upgrade them seperate argues to the fact of buying seperate