MB8611 can only reach about 1/3 (300 Mbps) of the speed I paid for (900 Mbps)

@XfinityJohnG​ , I just send a direct message. Please check.

Thanks in advance.

@user_9c78bd. We can definitely help with your speed issue and don't hesitate to make your own post when you have issues. The main factor is slow speeds is physical impairments and hardware issues. We recommend CAT 6 or above cables and a computer with a 1GB+ port. I checked on your signal and there are some issues that might require a technician. Direct message your name and address and we can work on it.

Make sure you are signed into forums

1. In the top right corner, you'll see a little chat icon(direct message) near the bell icon. 2. Click the "New message" (pencil and paper) icon

2. Hit the compose button to the right of "conversations"

3. In the 'To' line, type "Xfinity Support" there. A drop-down list appears. Select "Xfinity Support" from that list (an "Xfinity Support" graphic replaces the "To:" line)

4. Type your message in the text area near the bottom of the window

5. Press Enter to send it. An official employee, such as myself or whoever is first available, will respond. Thanks!

lots of the below errors repeating one after the other on the event log of the modem 
SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing
No Ranging Response received - T3 time-out

I have the same repeating error message and also have 

SYNC Timing Synchronization failure - Loss of Sync;CM-MAC......

Comcast checked my line remotely (while I was in a chat session) yesterday and saw something that might be an issue so I setup a visit from one of their technicians.

I also received a voice message this morning indicating that overnight an issue related to my service was identified and corrected (I assume remotely) and asking if I still want to keep my appointment with the service tech. I checked speed and it is still 300-400 Mbps so I will see if the tech finds anything.

Hi @user_f17ee0,

We would be more than happy to look into your Internet speed concerns. Could you please send our team a direct message with your full name and full address? Our team can most definitely take a further look at this issue.

To send a "Peer to peer" ("Private") message:

Click "Sign In" if necessary

• Click the "Peer to peer chat" icon

• Click the "New message" (pencil and paper) icon

• Type "Xfinity Support" in the "To:" line and select "Xfinity Support" from the drop-down list which appears. The "Xfinity Support" graphic replaces the "To:" line

Still having the same issue.  Did anyone get it resolved?  360 MBPS, which is fast, but I'm paying for 1 GBPS.  Other users on these forums are saying that the wrong bootfile is being used.  The fact that Xfinity still hasn't figured this out doesn't give me much hope...

@user_0d57e7, Please let us know if you are still having issues with your internet speed. We would be happy to help.