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Bought this modem thinking it would bring my download speeds close to the 2000 Mbps rated comcast Xfinity speed I subscribe to, but I am only able to get around 718 Mbps down and 5.8 up. After several attempts at trying to play with settings, OS, and multiple computers, I called in for support through Comcast. They tried their best with their magical keyboard skills, to no avail. Finally, a service technician was sent to determine the issue. After doing many more tests to coax cable, modem, router, cat5e & 6 cables, technician determined that the issue was at the modem.

He was able to show me on his device that the speeds coming in all the way to the modem were in fact 2247 Mbps down and 386 up. Unfortunately, there was no resolution, and the return window on Amazon has expired.

If anyone has found a way of increasing speeds, please share. Thx.

S33 is just a cable modem so you can confirm speed by testing only on direct connection and the speed you are getting is still not up to the speed plan you are in then we need to check the cable signal level on the modem GUI that is coming for your service provider.

http://arris.force.com/consumers/articles/General_FAQs/S33-Cable-Signal-Levels

S33 is just a cable modem so you can confirm speed by testing only on direct connection and the speed you are getting is still not up to the speed plan you are in then we need to check the cable signal level on the modem GUI that is coming for your service provider.

http://arris.force.com/consumers/articles/General_FAQs/S33-Cable-Signal-Levels


Thanks for your response.

Yes, we did do a speed test directly from modem to 2 different PCs (both with 2.5GbE nics). Speeds remained unchanged.

 

Here are screenshots of the status, info and config pages:

 

Thanks for any help.

Under downstream all the signals are in range; I suggest you to send us the upstream bonded channel signals to check all the signals are in range.

Thanks, here is the upstream:

 

Normally, Upstream bonded channels power level should be 45dbmv to 53dbmv. 

Since the power level for the upstream is not in a range, I suggest you to contact your internet service provider to adjust within the range. 

Moreover, S33 does not support the Next Gen plan. I shared Xfinity pdf for your reference:

https://assets.xfinity.com/assets/dotcom/projects/cix-4997_compatible-devices/2023.11.22%20Full%20List%20of%20Compatible%20Devices.pdf

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