netgear c6300v2 sustained speeds

[ignaav]

Hi there,

I have a Modem/Router c6300v2, and xFinity cable provider (400 Mbps / 20 Mbps). I have been testing the speeds for more than 2 weeks and the average is between 200-350 Mbps download, 5-11 Mbps upload. We had issues even worse (download speeds around 50 Mbps, and 0 Mbps uploads), so we contacted the Xfinity techincal support. They came twice home, and the last time the technician said that being a docsis 3.0, our modem-router could not sustain the speeds we are paying for... I checked the limits for this model and it says that it is 680 Mbps both download and upload.

My question is, is it possible that this model can not sustain 20 Mbps upload? (It seems absolutely ridiculous to me!!!)

Thanks

(All the test have been done with cat5e cable direct from the modem-router to a PC, Windows 10 64 bits, intel core i7 8700K, 16 GB 3200 Mhz RAM, Samsung M.2 SSD 1 GB... the configuration shouldn't be an issue)

[plemans]

A couple things. 

1. the speed rating is just what its rated for "up to". that all depends on the isp. Some isp's are requiring docsis 3.1 connections for faster speeds. 

2. it should still be able to hit 20mbps upload 

3. do you have a screen snip of its cable connections page and event logs? 

[ignaav]

Thanks for clarifying! I just wanted to make sure that that very slow upload speed should be sustained with the c6300v2, even being docsis 3.0 The last technician who checked the connection saw that we have a few splitters in the attic, I believe that must be the problem.

[plemans]

photos have to be approved by a moderator and can take a while. 
If you click on 'choose file" and add them that router, we can see them quicker