Change routing priority on iMac Our home phone/internet is down; dug up by council contractors, and won't be fixed for a week.
I am using an iPhone hotspot in the interim.

This works, but when I plug the Ethernet connection to my router into my iMac I can no longer access the internet.
I use the local network for file sharing and printing.

How can I stop the iMac from using the Ethernet connection for internet, or PREFERABLY set the priority for the hotspot to be higher when connected?

172.20.10.1 is the Hotspot IP

~$ netstat -nr
Routing tables

Internet:
Destination        Gateway            Flags        Refs      Use   Netif Expire
default            10.1.1.1           UGSc           53        0     en0
default            172.20.10.1        UGScI          13        0     en1
10.1.1/24          link#6             UCS             2        0     en0
10.1.1.1/32        link#6             UCS             1        0     en0
10.1.1.1           78:a0:51:16:bb:56  UHLWIir        31      156     en0   1192
10.1.1.9/32        link#6             UCS             2        0     en0
10.1.1.255         ff:ff:ff:ff:ff:ff  UHLWbI          0        1     en0
127                127.0.0.1          UCS             0        0     lo0
127.0.0.1          127.0.0.1          UH              1      300     lo0
169.254            link#6             UCS             0        0     en0
169.254            link#7             UCSI            0        0     en1
172.20.10/28       link#7             UCS             1        0     en1
172.20.10.1/32     link#7             UCS             1        0     en1
172.20.10.1        3e:2e:f9:2a:33:64  UHLWIir        15       12     en1   1181
172.20.10.5/32     link#7             UCS             0        0     en1
172.20.10.15       ff:ff:ff:ff:ff:ff  UHLWbI          0        1     en1
224.0.0/4          link#6             UmCS            2        0     en0
224.0.0/4          link#7             UmCSI           2        0     en1
224.0.0.251        1:0:5e:0:0:fb      UHmLWI          0        0     en0
224.0.0.251        1:0:5e:0:0:fb      UHmLWI          0        0     en1
239.255.255.250    1:0:5e:7f:ff:fa    UHmLWI          0       10     en0
239.255.255.250    1:0:5e:7f:ff:fa    UHmLWI          0       10     en1
255.255.255.255/32 link#6             UCS             1        0     en0
255.255.255.255    ff:ff:ff:ff:ff:ff  UHLWbI          0        2     en0
255.255.255.255/32 link#7             UCSI            0        0     en1
You can set the service order in the Network preference pane in Preferences.app.

Open Network preferences, click the small cogwheel icon below network connection list (next to the + and – icon), choose "Set Service Order…" in the menu.

Then you just drag the entries in the dialog (w/o typing all the interface names).

Btw., in the Network pref pane you can also delete unused network interfaces (– icon) or make them inactive (cogwheel menu).