[SOLVED] SB6183 Modem Overachieving at 560Mpbs on Speedtest?

[TedShred]

I have an Arris SB6183 cable modem where the specs state "Up to 373 Mbps" yet a speed test at various internet speed checker sites (e.g., Ookla) says I'm getting over 560Mpbs download speeds. How is that possible?

I'm paying for a 600Mbps pipe from Comcast and got the note that my currently modem doesn't support 600Mpbs (agreed) and should upgrade to take advantage of the plan. I have a new Motorola on the way but am curios how the Arris SB6183 was hitting those speeds.

 

[bill001g]

not sure where you get 373.

It says it is docsis 3 using 16x4. That has a theoretical speed of 686 ignoring that there is overhead. Now that does not mean the isp actually uses 16x4 on the segment to your house. Depends on many factors, some isp cable infrastructure is not good enough so they drop down 1 level. But if they dropped to 8x4 it would likely be under 300mbps.

 

[TedShred]

The 373Mbps spec came from the Xfinity site where they telling me I need a new modem. As you correctly called out, the Arris site notes up to 686Mbps for that modem which explains why I'm getting over 560Mbps. All makes sense (except why Xfinity posts that lower number). Thank you.