Speed issues C3700 - 100NAS with Xfinity and a 400Mbps service plan

[Johnkov67]

I just upgraded my plan through xfinity from 150Mbps to 400Mbps. My previous speed tests had results of 4.8 Down and 6.2 Up. Once they did their thing and my modem/router reset, I re-tested and got the results posted in the screenshot. Is there something I need to do in the settings of the router to increase the speed or is it something on the ISP's end? 

[FURRYe38]

Is this result with a wired PC or wireless device. Besure you test with a wired PC connected to the C series modem first. 

Try different devices and a different PC if possible. 

[Johnkov67]

I am on a wired PC. with about 15 ft of Cat5 between me and the router. 

[FURRYe38]

Try with a CAT6 cable. Different PC if you have one. 

Ensure your pc doesn't have any background running apps running while speed testing. 

[plemans]

Comcast requires at least a 16x4 modem for speeds >150mbps. Theoretically it gets up to 340 mbps but comcast doesn't rate it to that. 

With that being said, you're c3700 should give you faster speeds than you're currently getting. 

If you're testin over a hardwired connection with a gigabit device (make sure the device you're testing with is 10/100/1000) you should be doing better. 

Here's where I'd start. Connect your coax line right where it comes into the house. Remove all splitters, splices, extra cables, amplifiers from the line. Directly off the line coming in. Test from there and see what speeds you get. Also, post a screen snip of your connections page to make sure your line is good. This includes upload and download connections. 

If you're still testing low, try contacting comcast and having them resend the configuration file. I've had them send the wrong partitioning before. 

[FURRYe38]

The modem is a 8x4 modem. 

[plemans]

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@FURRYe38 wrote:

The modem is a 8x4 modem. 

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Yep, and its not rated >150mbps. Theoretically it allows up to 340 mbps but comcast doesn't certify it for that. I'm just saying that they require at least a 16x4 for >150mbps. 

[plemans]

I didn't mean to imply the c3700 was 16x4. I was just going over what comcast requires for certain service levels. Again, with that said, that device should still be getting better speeds than its reporting. 

[FURRYe38]

I presumed that. I was just posting the channel specs.