User authentication failed while log in Solaris 8 client on Linux NIS server.

Based on the NIS migration tests I did and another question I posted earlier on.

I tried to downgrade NIS linux encryption to DES to support solaris connection.
So I modified /etc/pam.d/system-auth as below,

password    requisite     pam_cracklib.so try_first_pass retry=3 type=
password    sufficient    pam_unix.so shadow nullok try_first_pass use_authtok
password    required      pam_deny.so

and then reset the user's password.
I can login the user's account from the linux client with no issue, but I just can't login from the solaris client using both telnet and ssh.

I checked the log message, and it kept showing the following messages.

Apr 13 17:05:05 lay8 sshd[21086]: [ID 800047 auth.info] Invalid user systest from 172.26.80.46
Apr 13 17:05:05 lay8 sshd[21086]: [ID 800047 auth.info] input_userauth_request: invalid user systest [preauth]
Apr 13 17:05:07 lay8 sshd[21086]: [ID 800047 auth.error] error: Could not get shadow information for NOUSER
Apr 13 17:05:07 lay8 sshd[21086]: [ID 800047 auth.info] Failed password for invalid user systest from 172.26.80.46 port 48485 ssh2
Apr 13 17:05:11 lay8 sshd[21086]: [ID 800047 auth.info] Connection closed by 172.26.80.46 [preauth]

I just can't figure it out. Did I miss something?
For more information,

# passwd -S systest
systest PS 2017-04-13 0 99999 7 -1 (Password set, DES crypt.)

/etc/ypserv.conf

# xfr requests are only allowed from ports < 1024
xfr_check_port: yes

# The following, when uncommented,  will give you shadow like passwords.
# Note that it will not work if you have slave NIS servers in your
# network that do not run the same server as you.

# Host                     : Domain  : Map              : Security 
#
# *                        : *       : passwd.byname    : port 
# *                        : *       : passwd.byuid     : port

# Not everybody should see the shadow passwords, not secure, since
# under MSDOG everbody is root and can access ports < 1024 !!!
*                          : *       : shadow.byname    : port
*                          : *       : passwd.adjunct.byname : port
172.26.80.0/255.255.248.0  : * : * : none
*                          : * : * : deny

Thanks.