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Kitchener, ON

[DSL] Subnetting with the Comtrend CT-5072T Modem (Made Easy)

As I was mentioning to a certain someone, I am creating several guides in these forums for a number of purposes. Hopefully, this guide will prove to be a valuable asset for consolidating network hardware down into a smaller configuration. In this example, I will be demonstrating how to establish a static /29 subnet from TekSavvy using the Comtrend CT-5027T Modem.

Before we begin, there is some basic information that you will need from TekSavvy (or other provider) to begin, so if you do not have any of the following information about your connection, you will first need to contact TekSavvy (or other provider) to obtain it. In this example, I am going to use the DSL connection information I was given, but you will need to substitute your information into the modem's settings when configuring it with this guide.

The information is:

DSL Connection:
•IP Address for PPPoE Link: 76.10.xxx.xxx
•Static /29 Subnet Range: 173.xxx.xxx.225 - 173.xxx.xxx.230
•Static Subnet Mask:
•PPPoE Username: ********@teksavvy.com
•PPPoE Password: <masked>

Key Modem Defaults:
•LAN IP Address:
•Username: root
•Password: 12345

Once you have this information, you can proceed to step 1 below.

Step 1 - Checking your Network Settings
To make sure that everything will go as planned, it is strongly recommended that you reset the modem to its factory defaults. You can do this by plugging the modem in and powering it up, then when it has fully booted up, press and hold the "reset" button on the back of the modem until your power light turns RED.

Then, make sure that your computer's network card is either configured to automatically assign an IP address, or set a static IP of with a subnet of and a gateway of Once this is established, you can then plug one network cable into your modem's LAN port and a switch and another network cable into your computer's network card and the same switch, then continue to step 2 below.

Step 2 - Configuring the PPPoE Link
From here, you will need to open a web browser. When it opens, point it to » and you will be brought to a page that looks like the example below:

When you see this page, click on the "Advanced Setup" link on the left side, then click the "Add" button that will appear in the middle of the page. Note that you will also see a link that says "Basic Setup", but for this kind of job, we're far from "basic".

In the ATM Configuration page you will see, you will want to adjust your settings to look exactly as follows, then click next:

In the next page, select PPPoE and match the following settings, then click "Next":

Next, you will be asked to enter your PPPoE login and configure the parameters of the connection. There are several check boxes that need to be changed here, so before you click "Next", make sure that all the check boxes are configured as follows:

Next, you want to give your PPPoE service a name that the modem can identify it as. Again, before clicking "Next", make sure that the check boxes are set as follows:

Lastly, you will be brought to a screen to review and confirm the settings. On your screen however, the "save" button will actually say "Save/Reboot" because you have added configurations. See this illustration:

You should then be brought to a page that looks like this:

Step 3 - Configuring LAN Settings
This is essentially the very last step of the process on this modem. To establish your LAN settings, after your modem has rebooted, click on the "LAN" link on the page you were on. It should bring you to the configuration page. You will want to substitute the first of your IP subnet block where I have mine. A little common sense will go a long way in this step, but it shouldn't be too hard to figure out. Make the settings resemble this:

Once this is all done, click the "Save/Reboot" button and you're all set. You can then assign your other 5 IP addresses to up to 5 other computers or devices using the gateway IP 173.xxx.xxx.225 that was assigned to the Modem's LAN.

This modem should be pretty straight forward, but if you have any problems, feel free to give me a shot and let me know. These configurations are the ones that have worked successfully for me, thus, they should work just fine for you also.