Ah you didn't see my update from a few days ago then.
"Turns out having the mesh node in the stereo cabinet is a bad idea with regards to my C-J Premier 6 pre-preamp... It's VERY sensitive to EMI".
So I simply need to move the node from its current location to about 20' across the room. No big deal and the effort is still way worth the improvement in wifi generally in our home vs. the extenders I'd tried previously.
Happy listening.