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user_34d603
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Sunday, December 14th, 2025

Basic v. Advanced Bridge mode

I would like to know:

  1. What is the difference between the Basic and Advanced Bridge modes?
  2. If I have a block of 5 static IPs, which mode should I use?
  3. Is there a specific port on the CGA4131COM that I should use to connect my router?
  4. Should I let the router obtain its configuration from the CGA4131COM or configure a Static WAN?

I ask because:

  1. I put it into Advanced Bridge Mode and let the router use Dynamic WAN to obtain its configuration from the modem; the router can ping the IP it is given but cannot ping either the IP address it is given or 8.8.8.8. 
  2. The same happens if I configure a Static WAN on the router and use the same values as given in Dynamic mode (above).   
  3. I have been working on this for about 20 hours now and cannot configure things on the router (a TP-Link ER605) such that I have internet connectivity.

Thanks in advance!

As an aside, does Comcast have any plans to issue modems that support VLANs to its business customers?  I should think this is a pretty common need.

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23 days ago

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Comcast_Eva

Official Employee

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32 Messages

24 days ago

Good morning @user_34d603 

Thank you for visiting the Comcast Business Forums 

 

Jumping right in to your questions, when enabling Bridge Mode, Advanced Bridge Mode is the default setting. To get to Basic, log into the router a second time, then click Basic. 

 

Difference between these: 

 

  • Advanced (CBR & CBR2): eRouter forwards only Xfinity WiFi traffic to/from the CMTS. Modem transparently bridges all customer Ethernet traffic to the CMTS. Use when you would like to retain the Xfinity WiFi hotspot. Advanced Bridge Mode leaves the Xfinity WiFi Hotspot active.
  • Basic (CBR & CBR2): eRouter is not disabled. Your WiFi hotspots and Xfinity WiFi hotspots are disabled in this mode. Modem transparently bridges all customer Ethernet traffic to the CMTS. In this scenario, you will have your own Router / Firewall that you want to receive the WAN DHCP IP address sent from the CMTS. Your device must be set to accept WAN DHCP. Required for SD-WAN.

When a modem is in bridge mode, the Static IP routing, LAN DHCP and other settings are disabled. A bridged modem will only assign dynamic public IPs to connected devices in the same manner as a basic cable modem.

 

If you have a block of 5 static IPs, you should configure your router to use the static IPs assigned to you. For connecting your router to the CGA4131COM, you can use any available LAN port on the gateway. It is recommended to manually configure a Static WAN on your router rather than allowing it to obtain its configuration automatically, as this ensures that your static IP settings are correctly applied.

 

(View more here: https://business.comcast.com/support/article/internet/using-a-static-ip) 

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user_34d603

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3 Messages

Thanks for your prompt reply. 

  1. I put the gateway into Router mode and the ER605 WAN into Dynamic IP 
  2. I then use the values given by the gateway's DHCP server to configure the ER605 WAN's Static IP
  3. I put the gateway into Bridge mode (Advanced or Basic)
  4. I reboot the ER605.  It correctly comes up with the Static IP I had configured in Step 2.
  5. The ER605 cannot ping 8.8.8.8 from its WAN interface.

I have yet to find a configuration that allows the ER605 to access the internet.  Thanks in advance for all suggestions.

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23 days ago

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user_34d603

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3 Messages

Specifically:

  • "What gateway IP should I use for my xx.yy.zzz.8/29 static block?"
    • Is it 69.245.136.1?
    • Or should it be something within my block?
  • "What subnet mask should I use?"
    • /29 (255.255.255.248)?
    • Or /30 (255.255.255.252) like DHCP gave me?
  • "The gateway 69.245.136.1 is unreachable from my static IP xx.yy.xx.zzz.14. How should routing be configured?"
  • "Do I need a static route configured on my router to reach the gateway?"

(edited)

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23 days ago

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Comcast_Billie

Official Employee

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117 Messages

 

user_34d603 Thank you for the additional information. I'd like to get a look closer at the account to better assist you. Please send us a DM to Comcast Business with your full name, address and phone number associated with the account to get started.

To send a direct message:
Click "Sign In" if necessary
Click the "Direct Message" icon 
Click the "New message" (pen and paper) icon
The "To:" line prompts you to "Type the name of a person". Instead, type "Comcast Business" there.
As you are typing a drop-down list appears. Select "Comcast Business" from that list.
A "Comcast Business" graphic replaces the "To:" line.
Type your message in the text area near the bottom of the window   
Press Enter to send it

 

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23 days ago

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