Diagnosing Slow Internet & Basic Internet Troubleshooting

[RogersRoland]

PROBLEM: I can’t connect to the internet from any of the computers on my network. How can I troubleshoot before calling in for help?

ANSWER: The problem most likely lies with either your modem or the configuration of your router (if you have one). Follow the steps below, in the order they appear, to try to fix your problem.

STEP 1: RESTART YOUR COMPUTER
Sounds basic, but this simple step often resolves minor issues relating to connectivity. You may also try shutting it down completely and then waiting a few minutes before restarting.

STEP 2: RESTART YOUR MODEM
Unplug your modem’s power cord, and if you have a router, unplug that as well. Then wait one full minute before plugging your modem back in. Wait for the lights on your modem to turn solid green (not flickering). If you unplugged your router, plug it back in and wait for it to connect to your modem. Now, wait up to 10 minutes before your modem goes online.

STEP 3: CHECK YOUR CABLES
Modem lights still not coming on solid? Ensure all power cables and wires are firmly attached to the correct ports.

STEP 4: SECURE YOUR CONNECTION
Some modems have a “link” or “PC” light that indicates whether or not your computer is connected to the modem. If this light is off or flashing, then your connection isn’t secure. If the modem is connected to your computer through a network card or port, then ensure that the cable is securely connected to the computer and modem. Never connect your computer to a modem using a USB cable and a network adapter cable. There should only be one cable connecting them.

Diagnosing Slow Internet and other Signal Related Issues:

In order to examine the DOCSIS Wide Area Network (WAN) data, you will need to log into your modem in order to access the DOCISIS WAN page.  Instructions & Models are as follows:

Cisco DPC3825

1. Directly connect an Ethernet cable from the modem to the computer.
2. Open a web browser and enter the following address to access the gateway login page: 192.168.0.1.
3. Login with:

• Username: cusadmin

• Password: password   (Or with user password if already set)

4. Click Status at the top of the page and the DOCSIS WAN tab.

Downstream Channels

                                Power Level       Signal to Noise Ratio

Channel 1:           0.0 dBmV             38 dB

Channel 2:           0.0 dBmV             38 dB

Channel 3:           0.0 dBmV             38 dB

Channel 4:           0.0 dBmV             38 dB

Channel 5:           0.0 dBmV             38 dB

Channel 6:           0.0 dBmV             38 dB

Channel 7:           0.0 dBmV             38 dB

Channel 8:           0.0 dBmV             38 dB

(Ideal/typical  level or range:            0.0 dBmV             36 – 40 dB)

Upstream Channels

                                Power Level      

Channel 1:           38 dBmV

Channel 2:           38 dBmV

Channel 3:           38 dBmV

Channel 4:           38dBmV

(Ideal/typical  level or range:           36-40 dBmV)

Hitron CGN2

1. Directly connect an Ethernet cable from the modem to the computer.
2. Open a web browser and enter the following address to access the gateway login page: 192.168.0.1.
3. Login with:

• Username: cusadmin

• Password: password   (Or with user password if already set)

4. Click Status at the top of the page and the CM STATUS tab.

Downstream Channels

Downstream Port:               1                 2                 3                 4                   5                  6                 7                   8

Frequency (MHz):          693.000     669.000     675.000    681.000      687.000     699.000    705.000       711.000

Modulation:                    256 QAM  256 QAM  256 QAM  256 QAM   256 QAM  256 QAM  256 QAM    256 QAM

Signal power (dBmV):   0.0              0.0              0.0              0.0               0.0              0.0              0.0                0.0      

Signal noise ratio (dB):  38.0           38.0            38.0           38.0             38.0            38.0            38.0             38.0  

Channel ID:                     17               13               14               15                16               18                19                20

(Ideal/typical  level or range: Signal Power  0.0 dBmV     Signal to Noise Ratio 36 – 40 dB)

Upstream

Port:                                               1                              2                            3                         4

Frequency (Hz):                     38596000            30596000            23700000

Bandwidth (kbps/KHz):        3200000              6400000               6400000

ModulationType:                  ATDMA                ATDMA                  ATDMA

Signal power (dBmV):             38.0                       38.0                        38.0    

Channel ID:                                 1                             2                             3

(Ideal/typical  level or range:           36-40 dBmV)      

Hitron CGN3 and CGN3ACR/CGNM

1. Directly connect an Ethernet cable from the modem to the computer.
2. Open a web browser and enter the following address to access the gateway login page: 192.168.0.1.
3. Login with:

• Username: cusadmin

• Password: password   (Or with user password if already set)

4. Click Status at the top of the page and the DOCSIS WAN tab.

Downstream                                                                     

Port  Frequency  Modulation    Signal        Signal   Channel

ID        (MHz)                                 strength    noise          ID                  

                                                        (dBmV)      ratio

                                                                           (dB)

1     645000000      256QAM         1.5       37.636         105

2     591000000      256QAM         2.1       38.605           97

3     597000000      256QAM         2.4       38.605           98

4     603000000      256QAM         1.7       37.636           99

5     609000000      256QAM         1.1       38.605         100

6     615000000      256QAM         0.9       37.636         101

7     621000000      256QAM         1.0       37.356         102

8     633000000      256QAM         1.6       37.356         103

9     639000000      256QAM         1.7       37.636         104

10    651000000    256QAM         1.1       37.636         106

11    657000000    256QAM         0.8       37.636         107

12    663000000    256QAM         1.1       37.636         108

13    669000000    256QAM         1.3       37.636         109

14    675000000    256QAM         1.8       37.356         110

15    681000000    256QAM         1.8       37.636         111

16    687000000    256QAM         1.5       37.356         112

17    693000000    256QAM         0.9       37.356         113

18    699000000    256QAM         0.5       36.61           114

19    705000000    256QAM         0.2       36.61           115

20    711000000    256QAM         0.7       37.356         116

(Ideal/typical  level or range:   0.0 dBmV    36 – 40 dB)

Upstream Channels

                               Power Level      

Channel 1:           38 dBmV

Channel 2:           38 dBmV

Channel 3:           38 dBmV

Channel 4:           38dBmV

(Ideal/typical  level or range:        36-40 dBmV)

What to look for:

Although each model is different, they must subscribe to the DOCSIS 3.0 signal requirements.  There will of course be a difference between the number of channels observed with 8 or 20 channels utilized for downstream transmission, however, the signal levels and signal to noise ratios will be the same when the same type of modulation is used, ie, 64 QAM, 256 QAM, etc.  

Downstream:

In this case there should be 8 operating channels for the Hitron CGN2 and Cisco DPC3825, and 20 operating channels for the Hitron CGN3 and CGN3ACR.  Ideally the downstream signal levels across all channels should read 0.0 dBmV.  It is normal to see a difference of three to four dBmV from the highest to the lowest signal level, and usually the signal levels will remain in a close grouping within that range.  The signal to noise ratios should be between 36 to 40 dB typically and there may be occasional high or low values that lie outside of that window by two or three dB. 

Upstream:

For the upstream, all modems should have a minimum of three channels running.  In some areas four upstream channels may be observed.  The signal levels should be in the 36 to 40 dBmV range typically.  Those values are the modem output power levels for channels transmitting back to the Cable Modem Termination System (CMTS).  As the external cables and connectors age, the CMTS and modem communicate with each other to set that power level, and with aging affecting the external cables and connectors, that signal level goes up to overcome the increasing losses in the cables and connectors.  If the modem can't supply enough power for three channels as the losses have become too great, it drops one upstream channel, thus running on two channels.  If there isn't enough power for dual channel operation at some point, another channel is dropped. At this point, in single channel operation, you will typically see severe degradation in the cable data rates. 

Signal level limits

Downsteam:  Signal power 0 dBmV (nominal) + / - 15 dBmV

Signal to Noise Ratio range (typical) 36 to 40 dB.  Ideally, this should not drop below a 34/35 dB level, especially when combined with low signal levels which range below 0 dBmV.

Upstream:  Signal Power 36 to 40 dBmV (typical) with an upper limit at 51 dBmV for three channel operation.  There should be a minimum of three upstream channels running.

Reach Out to us here on the Community Forums:

If you are experiencing poor performance on any modem and/or observe the following on your internet modem:

1. Missing one or more channels on the downstream side:
2. Missing one or more channels on the upstream side, i.e., only running on one or two channels;
3. Signal Levels which are down below -7/8 dBmV coupled with observed poor internet speeds or missing cable TV channels;
4. Signal levels above 7/8 dBmV coupled with observed poor internet or missing cable TV channels

If you have any doubt concerning your internet performance please post a question in the Rogers Community Forums along with your downstream tables, upstream tables and the results from a Rogers Speedcheck with an ethernet connected PC or laptop.  Any problems with wireless devices should first be approached from the ethernet connected point of view to ensure that the modem is operating normally.  Please post in any additional information such as whether or not you have services which include Rogers Cable TV and/or Rogers Home Phone, and if you are observing any problems with those services as well.  As well, indicate whether your home is an apartment, single family house, or other, as this may change the approach required to solve an internet problem.

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Thank You @Datalink for putting together this extensive troubleshooting document.