Retrieving Xbox traffic

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I have Wireshark installed on my PC and set to monitor wireless traffic (how my PC connects to the Internet). My Xbox is also attached to my home network (just the cable company's router) using only the wireless connection. I can monitor all traffic from my PC to the network, however, not traffic to & from my Xbox.

I thought that Wireshark would detect & report all traffic that came into the wireless network card on my PC, even if that traffic is not intended for the PC. Is that wrong? And if so, to monitor Xbox traffic do I need Wireshark installed and running on Xbox? Can that even be done?

Thank you.