i've found that key to making it work is to make sure that auto-connect to wifi access point (note that this is not a global system option but instead a per access point toggle) needs to be turned off...
networks:
- wifi access point(s)
- 10Gbe hardwired network
setup:
- connect to hardwired network
- setup all desired wifi connections to NOT automatically connect (in network settings, this is available as a toggle for each wifi network that you're already connected to)
- prioritize the 10Gbe network as described in previous posts above
- turn off wifi on mac (to disconnect from any currently/previously automatically connected wifi networks)
- turn on wifi on mac
result:
- connected only to hardwired network
- disconnected from wifi access points
- still able to use services that require wifi to be turned on/available (e.g. airdrop)
hope that helps.