Question problems routing cisco switch through AT&T router

Apr 20, 2021
I'm running into issues interfacing my cisco 2960-S switch to my AT&T router/modem (Arris BGW210-700) prior to switching to AT&T I had no problems. I have internet access and everything works great if the linksy 2500 router is in-between the AT&T router and the cisco switch's. I can ping the AT&T router and connect to the interface on my computer but when I move to CLI on the switch I can not ping the router but I can still ping a DNS server( or any other device on the network. if I remove the linksy from the equation the switch dose not even attempt to connect, the ethernet ports don't even light up. DHCP dose not seam to make a difference.

more back story to why I want to do this despite that have it working in the current config, I need to move one switch to the house to power the POE cameras and switch over to AP instead of the wireless routers currently everything is in an out building other than the AT&T router. The network is configured as shown below. Any help is greatly appreciated!!!

2960-S (1) (also used with no luck)
2960-S (2)

Reactions: SamirD
I am some what confused by your IP addresses and why you are using 2 different subsets.

These are simple layer 2 switches. They only use the IP address for management and you actually do not even need to set them if you were to do the configuration via a console cable. So if you were to plug a pc into port 1 and your router into port 2 the traffic goes directly no matter what ip if any is set on the switch. The only reason I can see that the port might not light up is if the cisco is detecting something like a spanning tree issue.....still most the cisco swithes I have seen the light just goes solid yellow when it is blocked.

This is the problem with using a commercial piece of equipment. You are going to have to learn much more than you average user.

Cisco has many sub models on many of their lines. Some layer 2 switches are very stupid and others have lots of fancy traffic shaping and vlan support. This line if I remember correctly can not route between subnets. I forget they replaced them with a new model that had a "X" instead of a "S" in the name about 6 ot 7 years ago.

I would find the manual that explains how to factory reset them or at least delete the configuration. By default cisco switches will run in simple dumb switch mode out of the box.
Reactions: SamirD