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AD_MA
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1st Reply

5 Messages

Tuesday, January 30th, 2024 2:11 AM

Down speed reduced after CODA56 modem upgrade

Just registered a new modem (CODA56) to replace SB8200 on a legacy Blast! service (800/100mbps d/u) and while upload speeds went up to 100mbps - download speed went down to about 670mbps. On the old modem I was consistently getting ~950/20mbps down/up. Has anyone else see anything similar? I'm in metro-west MA. 

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Updated 

8 days ago

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XfinityAlyssaA

Official Employee

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1.1K Messages

4 months ago

Good evening @AD_MA, and thank you for reaching out on our Community Forums with your upload speed concerns. May I ask if you are testing while hardwired or over WiFi? Have you tested on multiple devices or just one?

 

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AD_MA

5 Messages

Hi,

Just for clarification - my concern is with the degraded download speeds, uploads are great.

The tests were done over the hardwire, apples-to-apples comparison on a same PC before and after the modem upgrade. I only have specific speed figures from that particular PC/location for "before" and "after" comparison, however other machines on the network are consistent with the download speeds I am observing. When tested on the previous modem the download speeds were consistently in the upper 800mb and often in the upper 900's (excluding occasional slow downs typical of peak times, etc.). With the new one the speeds are fairly consistently in the mid to low 600's, so ~200Mbps drop.

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4 months ago

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XfinityAlyssaA

Official Employee

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1.1K Messages

Thank you for confirming that you have tried those troubleshooting steps @AD_MA, we really appreciate it. We'd be happy to take a closer look at your signal levels and troubleshoot further. If needed, we'll schedule one of our expert technicians to come take a closer look. Since it is a new modem, it may also be possible that it needs a provisioning signal to ensure it is provisioned properly for your speed tier. To get started, can you please send us a Direct Message with your first and last name along with the service address on the account? To send a "Direct Message" ("Private") message: Click "Sign In" if necessary

  • Click the "Direct Message 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
  • Type your message in the text area near the bottom of the window
  • Press Enter to send it

We look forward to working with you further. 

 

I am an Official Xfinity Employee.
Official Employees are from multiple teams within Xfinity: CARE, Product, Leadership.
We ask that you post publicly so people with similar questions may benefit from the conversation.
Was your question answered? Please, mark a reply as the Accepted Answer.tick

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4 months ago

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XfinityAlyssaA

Official Employee

 • 

1.1K Messages

4 months ago

Thank you for those additional details @AD_MA, and confirming that the issue is with the download speeds not uploads, my apologies for misreading initially. May I ask what troubleshooting steps you have tried so far for example, have you tried power cycling your modem?

 

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AD_MA

5 Messages

4 months ago

I power cycled just the modem 2 or 3 times by itself, then together with router/gateway that's sitting behind it, replaced copper eth cable between modem and router, replaced/swapped eth switch between computer-gateway/router-modem. Nothing seems to make any significant difference. 

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AD_MA

5 Messages

3 months ago

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CCJodie

Problem Solver

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1.3K Messages

 

AD_MA Hello, I would like to look more into this for you. Please send us a direct message with your full name and service address. 

Here are the detailed steps to Direct Message us:

• Click "Sign In" if necessary

• Click the "Direct Message" icon (upper right corner of this page)

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

• Type "Xfinity Support" in the to line and select "Xfinity Support" from the drop-down list

• Type your message in the text area near the bottom of the window

• Press Enter to send your message

 

I no longer work for Comcast.

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3 months ago

0

user_36rpnc

2 Messages

10 days ago

Was there a resolution for this issue?  I have an exact same issue with my new CODA56 modem. I have the Blast service with 800/100 mbps dn/up and with my old modem of MB8600 I was getting ~760/25 mbps dn/up and since CODA56 was installed, the update has gone up but download went down significantly averaging ~400/110 mbps dn/up.  Tried doing the support with Xfinity and initially they said I may have a bad modem, so I returned and got a new piece, but the issue remains.  After that Xfinity support just tried selling me an upgrade to gigabit which does not make sense since. Eager to know if someone got this resolved or I should just downgrade my plan.

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user_lkvgp8

2 Messages

Similar experience, 440/60+ (or so). As other/s recommend, who has some had success with forcing a modem update with2 or 3 restarts, I initiated four or five restarts. This did not work for me. Still 44/60-ish. I returned the CODA56 and went back to the Arris S3 and I'm getting 850/40.  I may try again in 9 months. The reviews on Amazon have been mostly good from users having better success than I. 

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10 days ago

0

AD_MA

5 Messages

10 days ago

I'm my case it looks like it has something to do with Coda not properly auto negotiating speeds on the LAN link side. After I swapped to a different router the issue mostly resolved itself, but I ended up returning it until there's a better unit available.

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user_lkvgp8

2 Messages

Thanks. I did restart the router as well as the CODA56. 

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10 days ago

0

user_36rpnc

2 Messages

Thanks. Will try swapping the router to see if it changes but doubt it will improve for my case, since I also connected the PC directly to the modem and was still getting ~400 only.

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10 days ago

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XfinityEricB

Official Employee

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1.2K Messages

 

user_lkvgp8 If you have issues with the next time you get a new device, please let us know. We can try a few steps to see if it corrects the issue when getting the incorrect speeds. 

 

I am an Official Xfinity Employee.
Official Employees are from multiple teams within Xfinity: CARE, Product, Leadership.
We ask that you post publicly so people with similar questions may benefit from the conversation.
Was your question answered? Please, mark a reply as the Accepted Answer.tick

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8 days ago

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