That's a useful piece of data: I'm using Intel Macs with older (10.14, 10.15) OS versions but if the problem happens with the latest hardware and software then it's probably neither of those. I rolled back to Unraid 6.9.2 and the SMB issue is gone. Will live with the macvlan warnings for now since they don't seem related to any actual problems. I have the unmounting issue with Time Machine shares as well as ordinary SMB shares.