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Proven Solutions for Fixing Slow Xfinity Upload Speed

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If you’re struggling with slow upload speeds when sending attachments or participating in video calls, your Xfinity internet may not be up to par. This article provides valuable information and effective solutions to enhance your upload speed and online experience.

Plus, you could save yourself $150 in technician fees with these tips.

The Root of Slow Xfinity Upload Speeds

Before searching for solutions, it’s important to accurately measure your upload and download speeds and compare them to the speeds listed in your Xfinity contract.

Conducting a single speed test in your browser may not provide accurate results, so consider the following steps for a more reliable reading:

  • Run three different tests in incognito mode using Ookla, Xfinity, and Google.
  • Test your speed through the xFi app.
  • Conduct speed tests on multiple devices, including a laptop and smartphone.
  • Test your speed while directly connected to your modem.
  • Disable your firewall, antivirus, and VPN before conducting a test.
  • Monitor CPU and memory usage during the test via Task Manager.

When Upload Speed Matters

It’s essential to determine if your slow upload speed is impacting your online activities that require a decent upload speed, such as:

  • Video conferencing on Zoom or Skype
  • Sending attachments in emails
  • Sharing photos on social media
  • Livestreaming video games

When Download Speed Matters

The following online activities are unlikely to be affected by a low upload speed:

  • Browsing websites
  • Downloading files
  • Watching videos on YouTube
  • Streaming Netflix or Spotify content

Upload Speed Lags Behind Advertised Speeds

After conducting your speed tests, compare the results to the speeds listed in your Xfinity contract. As of the time of writing, Comcast offers the following plans with specified download and upload speeds:

PlanDownload SpeedUpload Speed
CONNECT50 Mbps10 Mbps
CONNECT MORE100 Mbps10 Mbps
FAST300 Mbps10 Mbps
SUPERFAST600 Mbps20 Mbps
ULTRAFAST900 Mbps20 Mbps
GIGABIT1200 Mbps35 Mbps
Xfinity Internet plans along with download and upload speeds

If your test results match the speeds listed on the table, upgrading your plan may be necessary.

Unfortunately, Xfinity does not offer additional options to boost upload speeds as they prioritize download speeds, given the average user spends more time downloading content.

If your speeds are significantly lower than listed in your contract or have decreased unexpectedly, proceed to the next section for solutions.

11 Solutions to Improve Xfinity Upload Speed

Based on feedback from Xfinity users, we’ve compiled a list of solutions ranked from the most helpful to the least. Common causes of slow upload speeds include outages in your area and faulty cables or splitters. Try these solutions one by one until you find what works best for you.

1) Verify Area Maintenance or Outages

Check if there are any outages in your area by entering your address. If there is an outage, simply wait for Xfinity to resolve the issue.

Xfinity maintenance or outages in the area
Xfinity notification about the outage / Image: Pigtou.com

2) Check Line Condition

You can access the Configuration Manager to determine the real-time specs of your line and ensure it’s in good condition. Follow these steps to access the Configuration Manager:

  • Connect to Wi-Fi
  • Open a new browser tab and type or
  • Enter “admin” in the username field
  • Enter the password listed on the bottom label

You should see two tables: Downstream and Upstream. For issues with upload speed, you have to make sure that each channel of Upstream table are within the recommended values:

  • Upstream power (Pwr): between 35 and 51 dBmV
Check Your Line Specs in Xfinity Configuration Manager
Verify Pwr values of each Upstream channel / Image: Pigtou.com

If any of the channels are NOT within recommended ranges, there is an issue with your line. Contact Comcast and book an appointment with a technician.

Note that not all modems allow you to access Configuration Manager.

3) Check Coax Cable Compatibility

Make sure that your coax cable is RG6, especially if you live in an older house. An RG59 cable will limit your download speed to 500 Mbps and can also degrade your upload speed.

Look for the cable type printed on the cable itself.

In case your house has a lower-grade coax cable, replace it with RG6 cable to maximize the Internet speeds.

Additionally, inspect your coax cable for damage, reconnect the F-connector, and clean it from dirt and rust.

4) Replace Cable Splitters

Cable splitters are a common cause of issues with internet connection and speed. Try removing cable splitters and testing your connection, or purchase new splitters from Amazon or Walmart.

You can also test your splitters with a cable tester. All you need to do is to connect cable tester to both ends of the cable splitter with the coax cable and check if it passes the test (green light means the splitter is OK).

Note that there should be a maximum of one cable splitter per line. Comcast can replace faulty cable splitters outside of your home, but you are responsible for splitters inside.

Remote any cable splitters
Replace cable splitters / Image: Pigtou.com

5) Test Alternative Wall Outlets

Examine your home for alternative coax wall outlets as the one you’re currently using may be in poor condition. If this fixes your issue, scheduling an appointment with an independent technician is the most cost-effective way to repair your wall outlet.

6) Check Wired Connection

Connect your laptop to the Xfinity modem using an Ethernet cable (yellow port). If your upload speed returns to normal, the issue is with your modem. Replace it at your local Comcast store.

Hardwire Xfinity Router to Your PC to Test Connectivity
Hardwire Xfinity router to the PC / Image: Pigtou.com

7) Investigate Hardware Issues

We previously discussed how to properly test your internet speeds. Sometimes hardware issues can cause slow upload speeds. Conduct speed tests on multiple devices with Firewall, Antivirus, and VPN disabled, and in incognito mode.

Monitor CPU and memory metrics during the tests, and ensure that they are not too high.

7.1) Update Network Drivers

If you’re experiencing slow upload speeds only on your PC or laptop, try updating your network drivers. Here’s how:

  • Open Device Manager
  • Go to Network Adapters
  • Right-click on each adapter and select Update Driver, then Search Automatically for Driver.

8) Replace Your Modem at Local Comcast Store

If you suspect your modem is the cause of your slow upload speed, consider visiting your local Comcast store for a replacement. A phone call before your visit may not be necessary, but it won’t hurt to make one just to be sure.

9) Request a Diagnostic Check from Comcast

Call Comcast and request to be transferred to the “Advanced Wireless Gateway Repair” team.

They will run a health check and perform necessary diagnostics to identify the issue with your internet connection.

With access to your lines and signals, the Comcast team may be able to resolve the problem quickly and efficiently.

10) Reboot the Modem

To refresh your Xfinity modem, simply unplug the power cord for five minutes and then plug it back in. Wait for 15 minutes for the modem to connect again, then run a speed test to check for improvement.

11) Hard Reset the Modem

Locate the reset button at the back of your modem and hold it for 30 seconds to perform a hard reset. Wait for 15 minutes for the modem to connect again and reconfigure your WiFi admin and password.

If your modem does not have a dedicated reset button, use the WPS button at the front of the device.

Finally, run a speed test to verify the improvement in upload speed.

Hard Reset Xfinity Router by Pressing Reset or WPS Button
Hard reset your Xfinity gateway / Image: Pigtou.com


Xfinity upload speeds can be improved with the solutions mentioned in this article. If your speeds are lower than the speeds listed in your contract, there are 11 solutions to try before contacting a technician. You can save yourself $150 in technician fees by verifying area maintenance, checking line conditions, coax cable compatibility, replacing cable splitters, testing alternative wall outlets, and more.

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Pigtou Editorial Team

A group of tech enthusiasts who find pleasure in troubleshooting and resolving various issues. When we're not engaged in writing, we typically enjoy playing table football or spending time with our office dog.
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