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Trying to configure my home network. I set up the router, connected its uplink to the 4141 and put the 4141 in bridge mode. The 4141 won't provide an internet connection.
You're connecting an unmentioned router to your Technicolor CGM4141? If so, yes, the CGM4141 is just a connection to your router. The CGM4141 will only move data from one network (Cox) to another network (Your router). The Bridge only operates at the Data Link layer so it's not concerned with any routing protocols.
If your CGM4141is in Bridge mode, only its LAN Port-1 is active. If your CGM4141is in Bridge mode, it also changes its IP address to 192.168.100.1.
If you don't have Internet service, that'd be a connectivity problem between your client and the unmentioned router. They need to point to the IP of your router. Can you connect a client to a LAN port of your router?
Ah, it changes its IP! That means I have to tell the router a different default gateway, which is probably why I couldn't get a connection.But I'm correct about bridge mode, right? It just shuts down DHCP and wifi on the 4141 and turns it into a plain cable modem with one ethernet port that conects to the WAN port on the router?
You are correct about the bridge. It just turns the 4141 into a modem.
Does this mean you have to change the subnet mask from 255.255.255.0 to 255.255.0.0?
After you connect to the LAN port of your router, your router will configure itself. You don't have to enter an IP address or subnet.