Exact same problem with xav ax100.
No problems with OG XL on 8.0
I think this thread makes it pretty clear this is a pixel 2 XL issue
Thought I would add a working configuration for others with the Sony receiver. No disconnects for the past couple of weeks.
Sony xav-ax100 (1.02.06)
Connected Anker USB 3 6 ft powerline+ A to C directly to back of device
Pixel 2 XL
Prior Google USB cable connected via Sony extension cable did not work. Never tested the new cable with the Sony extension, that may have worked as well.