Comcast Internet Repair
Comcast internet service is an excellent value. Yet, the Comcast network is complex. Follow us as we guide you from ordering the proper service, modem settings, your building coax plant, to finally outside coax transmission lines and fiber node issues.
We Require Business Grade Internet Service
- Upgrade from older SMC 8014 modems. Newer modems have better electronics and thus allows for higher speeds.
- Business grade service has a higher level of response and technical support.
- Business grade service allows a static IP. Static IP allows us to monitor your service.
- If sharing the Comcast with any data, choose one up from the base package.
Modem Performance Issues
- Comcast modems share frequencies on the coax mainline with their neighbors before the signals are aggregated to neighborhood coax-to-fiber hub. At times, modems may shift to less congested frequencies. This switch should happen within 50 ms but in an abnormal condition, this switch can take up to a minute. During that time, no data is transmitted. Any VPN's will drop. Consider replacing the modem.
- Go to firewall settings and disable "Gateway Smart Packet Detection".
- Comcast advises frequent modem reboots to improve performance. If you must reboot more that once/month, ask for a new modem.
- Ask for old SMC 8014 modems to be replaced.
Your Building Coax Cabling Must be Perfect
- The cable modem must be installed next to your router in your computer area/room and on a UPS.
- The cable drop from the mainline to your modem must be RG11 cable.
- Remove old HBO filters from the tap plate used in the days of an analog cable TV.
- Replace the splitter between outside cable and cable modem with a quality two-way splitter (as pictured) with a favored power port for the cable modem.
- We discourage sharing of cable with TV or cable dial tone boxes as this is a point for noise and power loss.
- Fix the temp mainline splitter installed when your neighbor got Comcast and the 3rd party installer split your tap and cut your signal in half.
Verify Signal Quality Levels in Your Cable Modem Diagnostic Page
Comcast service delivery is like municipal water service delivery. It's a system of interconnected large and small diameter pipes. Comcast states that a working "water pressure" range is -15db to +15db with lower than -11db as being in the "yellow range". Unofficially, Comcast insiders state it should be at 0db for best performance. The picture below shows a Comcast SMC8014 cable modem diagnostic page with very low downstream power but acceptable (SNR) signal to noise ratio.
Good SNR is especially important if the downstream power can not be improved. Inside cabling defects such as a loose connection to a TV can cause poor SNR. On critical or new cable modem installs, we will discourage connection of cable TV until performance is proven. It is the customer's responsibility to correct any deficiencies on interior cabling.
You can't measure upstream SNR but you can extrapolate it by the upstream power the Comcast CMTS (head-end) commands the modem to transmit to push it's signal back to Comcast.
This is the View from Your Cable Modem Diagnostic Web Page:
Verify Signals with Comcast: (This Gets a Trouble Report Made)
Above modem performance must be within normal bounds for a week according to Comcast Scout or Grandslam systems.
Typical Scout Report health Check Report:
These reports show data marked as green, yellow or red. This report is all green.
|IP Address of Modem||220.127.116.11|
|Current CMTS Status||ACTIVE|
|Device Make/Model||SMC Networks SMCD3G-CCR|
|Device Up Time||104 days 9:14:35.05|
|Docsis Capability||DOCSIS 3.0|
|Downstream Signal Quality (SNR)||35.0|
|Modem Lost Syncs||1|
|Receive Power Level (downstream)||0.1 Dbmv|
|Receive Power Level (upstream)||2.8 Dbmv|
|Serial Number of the Device||H29421C3C4|
|Transmit Power Level (upstream)||48.0 Dbmv|
|Upstream Signal Quality (SNR)||32.0|
|Current Device Status||6(Online)|
|End of Life Status||No|
|Modem Boot File||d11_m_smcd3gccr_bcistarter_c05.cm|
Your signal quality goal....
|Minimum specs||Best we have seen|
|Down Power in||>= 0 db||0 db|
|Down Signal-to-noise (SNR)||> 32 db||> 37 db|
|Up Power||< 42 db||< 35.5|
Ground the Cable per National Electrical Code Section 800-33
- Cable Grounding. The metallic sheath of communications cables entering buildings shall be grounded as close as practicable to the point of entrance or shall be interrupted as close to the point of entrance as practicable by an insulating joint or equivalent device.
- The grounding conductor shall not be smaller than No. 14. The grounding conductor shall be run to the grounding electrode in as straight a line as practicable.
- Bonding of Electrodes. A bonding jumper not smaller than No. 6 copper or equivalent shall be connected between the communications grounding electrode and power grounding electrode system at the building or structure served where separate electrodes are used. Bonding together of all separate electrodes shall be permitted.
Above picture shows a Comcast Box that has NOT been grounded. Arrows indicate where grounded connection should be.
Mainline Tap Problems
Pictured above is a cable mainline connected to a mainline amplifier and to the right a two position mainline tap plate.
Two RG-6 coax drops come off the tap plate. One has a blue tag and the other has a yellow tagged HBO channel filter.
In this picture, installing a new (third) connection for a new customer would require the independent installer to first call the cable company to convert the two (2) position tap plate to a four (4) position tap plate, then the installer would need to make a second trip.
Or, to get his "paid per the job" install done, the installer may install a 2-way indoor splitter and then call the office to get the main line tap plate changed. On the later scenario, the customer who gets split, may be forced into a marginal power level condition. Plus, they will have two unexpected service interruptions. Once the single available connection is split, the second when the tap plate is properly converted to a 4 tap plate and then the new connection dedicated to it's own tap. They may also have marginal power levels and thus marginal service in between splits.
Pictured above is a four position mainline tap with one unused position properly
capped to prevent RF intrusion. Orange RG-6 direct burial cable is used. The
cable may turn yellow with age and exposure to the sun's UV rays.
Inspect your building drop from the mainline tap and insure that none of the above issues exist.
At some point past the copper coax main lines, the copper coax coverts to glass fiber lines. This is called the fiber node. These nodes can misbehave and cause problems for your neighbors and you. A fiber node feeds from 25 to as many as 300 businesses.
We have software that can detect these node problems by analyzing your Internet and those of your neighbors. We then correlate issues.
Refer Us to Comcast Users Next Door, We Both Benefit
We certainly love business referrals. Referrals to your neighbors are the #1 thing you can do to help monitor complex Comcast quality issues. When we see simultaneous issues from 3 or more otherwise healthy Comcast subscribers on the same node, we can submit an engineering ticket to Comcast to check the areas for issues.