Obviously there is a problem with the network setup on one or both Macs. Unfortunately, network issues are not much my strength. About the best I can offer there is to reboot the Macs after changing the network settings and see if that helps. Also, make sure that you "Apply" those settings when you close the Sys Prefs > Network panel.
At this point, I'd take a shot at making the data transfer with wi-fi while the Macs are setup in close proximity, cross my fingers and hope for the best.
Or I would make a Time Machine backup of the old Mac on an external drive and use that with Migration Assistant.
Back up your Mac with Time Machine - Apple Support
Otherwise you'll have to correct the networking issue before you can use that connection.
I'm sure there are folks here in the Communities who know this stuff inside out.
Best of luck. 🍀