When I configure a service file in systemd for my /usr/sbin/sshd file, 
I write a dependency statement such as After=network-online.target. 

...
[Unit]
Description=OpenSSH server daemon
Documentation=man:sshd(8) man:sshd_config(5)
After=network-online.target sshd-keygen.target
Wants=sshd-keygen.target
...

However, when I configured some special IPv6 addresses for my network adapter,
 I restarted the machine and found that the bind function of sshd failed to 
 bind such IP addresses. The reason is that when the bind function is called, 
 the IPv6 address is not in the neighbor discovery state 
 and does not take effect completely. 
 
 Therefore, I wonder whether the bind function policy in sshd can be modified accordingly.
 For example, the network address status can be detected first.