Here are the commands and corresponding errors…
debian@br-lxd:~$ lxc config device list haproxy
myport443
myport80
myport8000
debian@br-lxd:~$ lxc config device remove haproxy myport80
Error: Invalid devices: Not an IP address: localhost
debian@br-lxd:~$ lxc config device add haproxy myport801 proxy listen=tcp:0.0.0.0:801 connect=tcp:127.0.0.1:801
Error: Invalid devices: Not an IP address: localhost