FWIW, I tried ethernet for migrating from one iMac to another and it was a total failure (I didn't spend time trying to figure out why). When I switched to firewire (via a 400 - 800 adapter), it went smoothly in about 45 minutes.
Jon
macOS 11.7.10, iMac Retina 5K 27-inch, late 2014, 3.5 GHz Intel Core i5, 1 TB fusion drive, 16 GB RAM, Epson SureColor P600, Photoshop CC, Lightroom CC, MS Office 365
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