Hello - I was wondering if anyone can shed any light on my situation.

Setup: I have x4 Eero Pro 6 devices (1 Gateway + 3 meshes) dotted around the house.  My living room mesh typically gets at most 200Mbps on Wifi but as low as 80-100Mbps depending on the device (e.g. my Chromecast).  Today I setup a 4-way LAN switch plugged into port 1 of this device with a 1gbps ethernet cable.  To this switch I have connected 4 devices each with a 1gbps ethernet cable.  A speed test on these devices gets about 300-350Mbps  from the Eero so much better than the Wifi which was choppy at times.

The problem is, since I've set this up, the normal wifi speed (typically around 200Mbps) for my normal wifi devices (e.g. phone, laptop) has dropped significantly down to about 70Mbps.  I have tested this on my phone (S23 Ultra) and macbook pro both of which would always get around 200Mbps in and around the living room.  When connected to my Kitchen Eero the speed goes back up to around 200-250 as expected.

My question is: is there a technical reason based on my setup that the Wifi speed for the Living Room device has dropped (e.g. does the wired connection to the LAN switch somehow eats into the available bandwidth for Wifi?).  As you can tell I'm not technical with networking at all so just curious what reasons there could be for this.

Thanks