Working great for months, I add a port and now my speakers are cutting in and out across the board

No radio? How else would they do Wi-Fi and Bluetooth that are both carried over radio?

Not an expert on the radio modules used but often Wi-Fi (2.4, 5, 6 gHz) and Bluetooth are on the same module.

Just an example, probably not the one Sonos uses.

https://www.nxp.com/products/wireless-connectivity/wi-fi-plus-bluetooth-plus-802-15-4/wireless-mcu-with-integrated-tri-radio-1x1-wi-fi-6-plus-bluetooth-low-energy-5-4-802-15-4:RW612

Edit to mention warnings and status checking require the dedication of very limited internal memory. The lowest memory cost option that solves the issue is likely best.

Could probably be done in the controller. It knows.

In the controller option solves part of the problem, maybe the biggest part these days.

For new folks trusting iffy AI suggestions, what about the browser access at x.x.x.x:1400?