Source routing for host

Just can't work out what the command is; hopefully simple for someone who knows. Debian 12 with two uplinks: wlan0 is the main connection but is quite unreliable and hp is 4G failover. I want one host (which doesn't use much data) to always use hp.

# Create a new route table.
$ sudo echo "2 solar" >>/etc/iproute2/rt_tables

# Set the default route on the new table.
$ sudo ip route add default dev hp table solar

# Route traffic from a specific host to the new table.
$ sudo ip rule add from 192.168.0.60 table solar

$ ip route show table solar
default dev hp scope link

That route show seems wrong -- the default is there but not the rule for the host. After a while -- I guess it takes some time to become effective -- the host loses its Internet connection. To undo it all:

sudo ip route flush table solar
sudo sed -i '/solar/s/^/#/' /etc/iproute2/rt_tables

I guess that ip rule add from... is wrong but I can't see what to do instead.