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Connection Troubleshooting Tips

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Cable Expert

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If you are experiencing any problems with your Comcast internet connection, the suggestions below may provide some assistance with identifying and potentially resolving the issue. If you are still experiencing any connection issues after following these suggestions, please start a new topic on the forums.

 

Check if there is an outage

The XFINITY My Account mobile app for iOS and Android devices can provide you with information in the event of an outage. You can also log into your Comcast account and click the check for service interruptions link.

 

Recent changes in your service

If you recently changed any of your Comcast services or had your service recently installed, verify with a Comcast representative that there are no provisioning or modem registration issues on your account.

 

Troubleshooting tools

  • Speed Experience Check - This tool attempts to analyze your connection and automatically troubleshoots some common issues.
  • IPv6 Readiness Test - Check to see if an IPv6 issue might be causing your symptoms.

 

Check your signal levels

To view your modem’s status page go to http://192.168.100.1 or http://10.0.0.1

 

Specification      Min             Max
Downstream Power Level    
* Cable Modems -10dBmV +10dBmV
* Gateways and EMTAs -7dBmV +7dBmV
Downstream Signal to Noise Ratio 35dB 50dB
Upstream Power Level +35dBmV +50dBmV
Upstream Signal to Noise Ratio 31dB -
Upstream Receive Power -2dBmV +2dBmV

Note: Not all modems will allow you to view the status page and some will have different URLs to access this info. If you are unable to access your modem’s status page, you can contact Comcast Customer Support and ask the support representative for these values.

 

Using an approved modem

If you've had your modem for awhile, it may have reached End of Life (EOL) status. You can view modem compatibility info by visiting the My Device Info site.

 

Powercycle all of your equipment

Try powering all of your network equipment off, wait a few minutes, then power all equipment back on. When performing this procedure, first turn off the computer; then unplug the power from the back of the modem. If you have a telephony modem you can use the reset button (if available) or remove the battery. If you are using a router, disconnect the power cord from this also. After a few minutes, start by plugging the power back into the modem first and wait a minute or two for the modem lights to indicate an online status. Then plug in the power to the router and wait a few moments for this to come online. Lastly, turn on the computer and try your connection again to see if the issue is resolved. You can watch the Reset Your Cable Modem or Voice Modem video to learn how to properly reset your device.

 

Inspect coax lines

Inspect as much of the coaxial cable line leading up to your cable modem for signs of extreme bends, cuts, loose or corroded connectors. If possible, try inspecting the coaxial lines from the point this cable enters your home up to the point where it connects to your cable modem. If you see a section of cable or any connectors that are damaged, try replacing the section of cable. Also, try disconnecting and re-connecting all of the coaxial connections that lead up to your cable modem to ensure each connection is tight, corrosion-free, and that the coaxial tip visible at each connection end is not bent. Coax should be RG6 with compression fittings.

 

Splitters

Each splitter that is added to your cable line will degrade the cable signal slightly and may cause slower connection speeds or frequent modem disconnections. Normally, you should have one main splitter installed where the cable line enters your home with one branch feeding to the cable modem directly and the other branch feeding to all the TVs in the home. If you have multiple splitters on the coaxial line leading up to your cable modem, try by-passing these splitters and running a single coaxial line directly to your cable modem, if possible. This may disconnect any TVs that may be connected from these splitters but if this improves your modem connection, the problem can be attributed to either a faulty splitter that needs to be replaced or a potential signal problem that may require a technician visit. Splitters should be of good quality and broadband compliant. The label should read 5-1000Mhz (or 1Ghz).

 

Routers

If you have a router connected to your cable modem that allows multiple computers to connect to the Internet, try bypassing the router to see if the connection improves. To bypass the router, disconnect the power cord from your cable modem and then connect one computer directly to the cable modem with one Ethernet cable. Once connected, plug the power cord back to the modem, wait for the modem lights to settle and indicate an online status and then try your connection again to see if the issue is resolved. If yes, then you may have a faulty router or you should troubleshoot the router firmware and settings to resolve the connection issue.

 

Check your IP lease time

Comcast routinely performs maintenance on the network to keep things updated and running smoothly. If you are still experiencing connection issues after the above suggestions have been tried, look for your IP lease time to see if there may be network being performed in your area. To see your IP lease time, in Windows, go to Start->Run and type cmd and press Enter (if you are using Windows 98 or ME, type command and press Enter). This should present a black DOS prompt where you will need to type ipconfig/all and press Enter. Look towards the bottom of the returned information for the Lease Obtained and Lease Expired lines – if this shows a time of approximately one hour, there may be some maintenance being performed on the network and you should try your connection again after a few hours to allow time for the maintenance to be completed.

Note: the IP lease time will generally be around 4 to 7 days.

 

Check your speed

 

 

Speed Tier Download Speed Upload Speed
Economy Plus grandfathered 3 Mbps 768 kbps
Internet 5 not available in all areas 5 Mbps 1Mbps
Internet Essentials 10 Mbps 1 Mbps
Performance Starter 10 Mbps 2 Mbps
Performance 25 West 25 Mbps 5 Mbps
Performance Northeast/Central 25 Mbps 5 Mbps
Performance West 50 Mbps 5 Mbps
Performance Pro Northeast & select West markets 100 Mbps 5 Mbps
Blast! Northeast 200 Mbps 10 Mbps
Blast! Grandfathered in previously available Atlanta and Nashville areas 75 Mbps 10 Mbps
Blast! West select markets 105 Mbps 10 Mbps
Blast! Pro Select Atlanta, Nashville and Chicago markets 100 Mbps 10 Mbps
Blast! Pro West select markets 200 Mbps 10 Mbps
Extreme 105 grandfathered 105 Mbps 20 Mbps
Extreme 150 Northeast - grandfathered 150 Mbps 20 Mbps
Extreme 150 Central 150 Mbps 20 Mbps
Extreme 150 West - not available in all areas 150 Mbps 20 Mbps
Extreme 250 West - not available in all areas 250 Mbps 25 Mbps
Extreme 300 Available in select markets of Atlanta and Nashville and in all of the Greater Chicago Region 300 Mbps 25 Mbps
Extreme 505 grandfathered 505 Mbps 100 Mbps
Gigabit Advanced consumer trial available in Atlanta, Nashville, Chicago and select Detroit regions 1 Gbps 35 Mbps
Gigabit Pro not available in all markets 2Gb 2Gb

Note: The above chart is designed to provide general information. All tiers listed are advertised speeds. If you are unsure of your speed tier, a Comcast representative can provide that information.

 

Update your operating system and security programs

Make sure your operating system is updated and make sure your antivirus, firewall, and anti-spyware/adware programs are up-to-date. Once you have updated your security programs, please make sure you run a complete antivirus and anti-spyware/adware scan on your computer.

 

Firewalls

Firewalls can cause problems if not properly configured. If you have a firewall installed on your computer and are having connection problems, try turning it off briefly.

 

Traceroutes and ping tests

Running a ping test or traceroute to an IP address can be a helpful tool to troubleshoot routing problems. However, there are some things that you should and should not do when running these tests:

You should...

  • Run a test to an IP address on the Internet, such as a web server, email server or other computer that should have high-availability and is designed to accept ICMP traffic.
  • Run a test to a local IP address on your network such as a router or another computer.
  • Run a test to your modem/gateway's local IP address, such as 192.168.100.1 or 10.0.0.1. This can help determine connectivity between your computer and your modem.

You shouldn't...

  • Run a test to a CMTS or node. The network interfaces in these pieces of equipment are designed to de-prioritize ICMP traffic and will provide false-positives.
  • Run a test to 75.75.75.75, 75.75.76.76 or other Comcast DNS server. These servers de-prioritize ICMP traffic and will provide false-positives.
  • Run a test to your modem/gateway's external IP address while on your network.
  • Run a test while connected to a VPN service.
  • Run a test while connected wirelessly, unless a comparison test will be performed while directly connected to the modem/gateway.

Running a traceroute

Sometimes it is helpful to run a trace if you are having difficulty with a specific destination or service.

  • Windows 7 or later: Click Start -> Run and type cmd and press Enter. This will open the command prompt/DOS window. When open, type tracert www.comcast.net and hit enter. When it is finished, you will see a Trace complete message. Right click, mark, drag over the text, copy by hitting "Enter", and then hit "Enter" again to paste the trace results into a subreddit post.

  • Mac OS X: Open the Applications -> Utilities -> Network Utility and select the Traceroute tab. Enter an address such as www.comcast.net and start the trace. When completed, copy and paste the results to your subreddit post using normal copy and paste methods.

Running a ping test

  • Windows 7 or later: Click Start -> Run and type cmd and press Enter. This will open the command prompt/DOS window. When open, type ping -t www.comcast.net and then press enter.

The output will look like this:

Pinging www.comcast.net with 32 bytes of data
Reply from 204.127.195.15: bytes=32 time=75ms TTL=46
Reply from 204.127.195.15: bytes=32 time=75ms TTL=46

Let this run for about a minute or so and press Ctrl and C to stop it. In the output, look for how often a Request timed out message appears and also look to see that the time=XXmspart of each reply is as low as possible - below 100ms under ideal circumstances. Right click, mark, drag over the text, copy by hitting "Enter", and then hit "Enter" again to paste the ping results into your post.

  • Mac OS X: Open the Applications -> Utilities -> Network Utility and select the Ping tab. Enter an address such as www.comcast.net, set the number of pings for about 100, and start the ping.

 

Message last edited by i-am-nerdburg on 1-23-2017

 

Contributors to this page: Jason1, EG, Action H53, madylarian, CajunTek, Jo, and others.




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