How do I force Migration Assistant to use Ethernet

Boot both Macs into Safe Mode according to How to use safe mode on your Mac and turn of WiFi on each in System/Network/WiFi settings pane and under Details uncheck "Automatically join this network". Move the Ethernet connection to the top of the list in that pane if

Note:  if you have a wireless keyboard with rechargeable batteries connect it with its charging cable before booting into Safe Mode.  This makes it act as a wired keyboard as will assure a successful boot into Safe Mode.

Then start Migration Assistant on the destination Mac and see if it will work.

You could also turn off the router/modem to assure no WiFi;

Try turning off your Wi-Fi router and run a direct Ethernet to Ethernet connection.

If that doesn’t work? Consider using Time Machine or a Clone on an external drive, which would be faster and more reliable.

vonlost wrote:

Thanks, but turning off router takes us completely offline for unknown hours/days!

Then use an external drive. An external HDD would be faster than Ethernet and an external SSD would be 5 to 10 times faster than an external HDD.

Yeah' Apple needs to update that article and/or move folks with over 100GB away from network migration. While it's not totally useless for those with 40GB to 60GB of data, but it should not even be considered for 200GB and up. Let along other issues like network speed, other traffic and general fussiness. Sadly they would also like you to pay for additional Cloud Storage.

Personally I keep Time Machine backups on an HDD and a CarbonCopyClones on an SSD. I used the SSD Clones for the last three big moves and it took less than an hour to migrate over 250+ GB to the new Mac's.

You're right but the longest it to me was about 6-8 hours and I ran mine over night.

In any case give the other method a go and see if it will work.