How to capture traffic of the device (router) I am connected with

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Hi all,

I have my small switch connected to main switch (Linksys) and my all home devices are connected to the main switch (Linksys), Now I want to capture traffic of linksys from my small own switch, what is the best way to capture, can anyone help me here?? I am new user of wireshark and before I was for OpenWRT, I got nice response from there, I am expecting from here too.

Thanks, Dhaval