CM1150V - Slow speeds on Xfinity

[djkid1985]

I purchased a CM1150V modem to use with Xfinity Gig Internet. However, I'm not getting anywhere close to the right speeds. I have done troubleshooting with Xfinity: 

• Reset modem physically using the reset button (several times)
• Xfinity reset the modem several times on their end. 
• Technician visited and said he was getting 960mbps to the coax, and one time through the modem, but not through my TP-Link Router. Tech advised to buy a new router. 
• Purchased Netgear Nighthawk RAX40. Same issue persists. 
• More resets/factory resets of both the modem and router. 

I should note, I've NEVER gotten any faster than 300mbps on the modem and I never saw the Xfinity tech's machine to know if he really got close to that on it. When I called Xfinity again today, the Tier 2 told me that Xfinity doesn't allow you to use your own modem for gigabit Internet and I had to rent theirs. If that's the case, why is this an approved modem on their website? 

Has anyone been able to successfully get close to gig speeds on this modem on Xfinity? 

[FURRYe38]

So do you get near 900Mpbs with a wired PC directly connected to the CM modem? 

What PC are you using for speed testing? 

[djkid1985]

I have never gotten more than 300Mbps directly wired to the modem. I have tried both a Lenovo and a Dell laptop, as well as an iMac.

I get the same speeds wired to the Netgear router, as well.

[FURRYe38]

What are the model# of these PCs? 

How old are these PCs? 

[plemans]

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I should note, I've NEVER gotten any faster than 300mbps on the modem and I never saw the Xfinity tech's machine to know if he really got close to that on it. When I called Xfinity again today, the Tier 2 told me that Xfinity doesn't allow you to use your own modem for gigabit Internet and I had to rent theirs. If that's the case, why is this an approved modem on their website? 

Has anyone been able to successfully get close to gig speeds on this modem on Xfinity? ---Yes

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yes, I've gotten gig speeds using the C7800, the cm1000, and the cm1100.  all on xfinity.

The tech was either lying or just trying to get you off the line. 

Do you have a screen snip of your modem cable connection page? (all of it)

What device are you testing on? 

What speedtest site are you using?