Adding a LXC remote server to Incus Server

Ccpy client.crt to LXC

Transfer the client.crt from your user on the Incus server (look for it somewhere under ~/.config/incus/), then transfer it to the lxc server

# List File
ls ~/.config/incus/
client.crt  client.key  config.yml  oidctokens  servercerts

# Copy `client.crt` to LXC Server
rsync -avp ~/.config/incus/client.crt ubuntu@lxc_server:/home/ubuntu

Add Incus client.crt to the LXC trust store

# add trust
lxc config trust add client.crt

# Displays the trust configurations for an LXD server.
lxc config trust list

+--------+------------------------+------------------------+--------------+
|  TYPE  |          NAME          |      COMMON NAME       | FINGERPRINT  |
+--------+------------------------+------------------------+--------------+
| client | client.crt             | ubuntu@xserver00       | 17a823c5a2b1 | 
+--------+------------------------+------------------------+--------------+

Add the remote legacy LXD server to Incus

# remote lxc server ip : 10.10.10.21 
# set name show on incus as `xserver01`
incus remote add xserver01 10.10.10.21

# If get the error
Error: json: cannot unmarshal bool into Go struct field Server.config of type string

# On the LXC host, unset any token identification that might have been set up:
lxc config unset core.trust_password

Reference