You don't need a gateway, and you certainly don't need DNS. You also don't need such a large mask. Just enter the IP address, for example, 10.10.10.20, and the mask. Depending on the format, either 24 or 255.255.255.0.
For testing, you can enter the IP address manually in the console.
#check the interface name (probably enp0s31f6)
sudo ip link show
#add address
sudo ip addr add 10.10.10.20/255.255.255.0 dev enp0s31f6
#test local address
ping -c 3 10.10.10.20
#test mesa card
ping -c 3 10.10.10.10
