Have DHCP for Wi-Fi and static IP for Ethernet? I'm trying to connect to a device over Ethernet and set a static IP for the Ethernet to talk to the device. When I do this, I can talk to the device but it kills connection to the Wi-Fi and I can't use the Internet. 

Is there a way to keep the static IP just for the Ethernet and keep the Wi-Fi connection as dynamic?
This Apple discussion sounds like what you're looking for, titled: Wi-Fi and Wired network load preference. This discussion shows a screenshot where you can augment the service order for the network connections.



Set your connections appropriately under their respective configurations (Wi-Fi vs. Ethernet) and then set the order so that the connection you've decided and configured as the Internet facing one is the one with higher service order than the other.

This should give you what you want.