CM1000v2 having poor speed test results

[Tom_Z]

Just bought a CM1000v2 cable modem. Went through set up with xfinity. It works but speed is very poor. I have 300 mbp service and speed test only shows 33 mbps. Xfinity says everything is fine on their end. I replaced a Arris SB6141 which was providing me 175 mbps so wanted to upgrade modem to faster one.  Any ideas what might be the problem?

Thanks

Tom

[FURRYe38 · Accepted solution]

Has the modem been factory reset. Press the reset button for 15 seconds then release.

It's also possible that you have a faulty unit which needs to be replaced. 

[Tom_Z]

Adding screenshot of cable connect details in case that provides any additional insight??

[FURRYe38]

Have the ISP check the signal and line quality UP to the modem. 
Be sure there are not coax cable line splitters in the between the modem and ISP service box. 
Be sure your using good quality RG6 coax cable up to the modem.

Be sure to test with a wired PC connected directly to the modem, remove any external wifi routers. 

[Tom_Z]

I have PC direct connected to modem with quality cat6 cables.  No spliters on incoming cox line.  Here is what baffles me.  I got fed up with slow speeds so reconnected old modem as a test to see how speeds were on it and found that my download speeds were consistenty around 250 mbps.  Now, that's not the 300 mbps that my plan offers but it is a heck of aa lot faster than the 35 I was getting with the CM1000.  I'm not an IT guy but am an engineer and my thinking is that this little test would suggest my signal coming in is fine and the issue is with the modem set up?  Am I thinking of this correctly and if so, what next to look at.  Xfinity points at Netgear and when I was on chat session with Netgear they point at Xfinity.  

[FURRYe38 · Accepted solution]

Has the modem been factory reset. Press the reset button for 15 seconds then release.

It's also possible that you have a faulty unit which needs to be replaced.