IPv6 has caused issues in the past with my ISP (T-Mobile Netherlands). It was disabled in network settings of the Eero system, I didn't change anything on the Mac or iPhone. I have enabled it again, I'll report back if that changes anything.

Disabling WiFi & Bluetooth on the phone (or disabling WiFi on the Mac) does seems to solve this for me, but isn't a long-term solution. Can we get a setting to force Xcode to use the cable, esp. now that the 15 Pro does support USB 3.2 Gen 2 transfer speeds if using the right cable. Reported FB13203790