dovecot authentication randomly temp_fail after update

Hi guys,

after hours of research i cannot solve this problem, so if anybody run into this problem please help!
I can receive emails and can send it, but the clients (mobile, desktop, roundcube) randomly disconnect or show errors.
Roundcube says:  AUTHENTICATE PLAIN: Temporary authentication failure.

I tried to reinstall dovecot, and cannot change default CWP dovecot.conf, but the problem is still persist.

Installed Packages
Name        : dovecot
Arch        : x86_64
Epoch       : 2
Version     : 2.3.21
Release     : 1
Size        : 16 M
Repo        : installed
From repo   : dovecot-2.3-latest

Code: [Select]

dovecot.log:
Oct 21 12:29:22 log(22867): Error: net_accept() failed: Bad file descriptor
Oct 21 12:30:12 master: Warning: Killed with signal 15 (by pid=23438 uid=0 code=kill)

test:
[root@w]# doveadm auth test test@example.com somepass
passdb: test@example.com [b]auth succeeded[/b]
extra fields:
  user=test@example.com
 
[root@w]# doveadm auth test test@example.com somepass
passdb: test@example.com [b]auth failed[/b]
extra fields:
  user=test@example.com
  [b]code=temp_fail[/b]
 
[root@w]# doveadm auth test test@example.com somepass
passdb: test@example.com [b]auth succeeded[/b]
extra fields:
  user=test@example.com
 
[root@w]# doveadm auth test test@example.com somepass
passdb: test@example.com [b]auth succeeded[/b]
extra fields:
  user=test@example.com
 
[root@w]# doveadm auth test test@example.com somepass
passdb: test@example.com [b]auth succeeded[/b]
extra fields:
  user=test@example.com
 
[root@w]# doveadm auth test test@example.com somepass
passdb: test@example.com[b] auth failed[/b]
extra fields:
  user=test@example.com
  code=[b]temp_fail[/b]

dovecot config:

[root@w]# cat /etc/dovecot/dovecot.conf
##
## Dovecot config file
##
listen = *
disable_plaintext_auth = no

protocols = imap pop3 lmtp sieve
auth_mechanisms = plain login

passdb {
driver = sql
args = /etc/dovecot/dovecot-mysql.conf
}

passdb {
driver = sql
args = /etc/dovecot/dovecot-token.conf
}

#userdb {
#driver = prefetch
#}

userdb {
driver = sql
args = /etc/dovecot/dovecot-mysql.conf
}

mail_location = maildir:/var/vmail/%d/%n
first_valid_uid = 101
first_valid_gid = 12
mail_plugins = quota
mailbox_idle_check_interval = 30 secs
maildir_copy_with_hardlinks = yes

service imap-login {
inet_listener imap {
port = 143
}
inet_listener imaps {
port = 993
ssl = yes
}
process_limit = 500
}

service pop3-login {
inet_listener pop3 {
port = 110
}
inet_listener pop3s {
port = 995
ssl = yes
}
}

service lmtp {
unix_listener /var/spool/postfix/private/dovecot-lmtp {
group = postfix
mode = 0600
user = postfix
}
}

service imap {
vsz_limit = 256M
}

service pop3 {
}

service auth {
unix_listener auth-userdb {
mode = 0660
user = vmail
group = mail
}

# Postfix smtp-auth
unix_listener /var/spool/postfix/private/auth {
mode = 0660
user = postfix
group = postfix
}
}

service auth-worker {
}

service dict {
group = mail
unix_listener dict {
mode = 0666
user = vmail
group = mail
}
}

service managesieve-login {
inet_listener sieve {
port = 4190
}
service_count = 1
process_min_avail = 0
vsz_limit = 64M
}

service stats {
   unix_listener stats {
     mode = 0662
   }
}

service managesieve {
}

ssl = yes
ssl_cert = </etc/pki/tls/certs/hostname.bundle
ssl_key = </etc/pki/tls/private/hostname.key
ssl_verify_client_cert = no

lda_mailbox_autocreate = yes
lda_mailbox_autosubscribe = yes

protocol lda {
#mail_plugins = sieve
mail_plugins = quota sieve
postmaster_address = postmaster@your-domain.tld
}

protocol imap {
mail_plugins = quota imap_quota trash
#mail_plugins = trash
imap_client_workarounds = delay-newmail
}

lmtp_save_to_detail_mailbox = yes

protocol lmtp {
mail_plugins = quota sieve
#mail_plugins = sieve
}

protocol pop3 {
mail_plugins = quota
#mail_plugins =
pop3_client_workarounds = outlook-no-nuls oe-ns-eoh
}

protocol sieve {
managesieve_max_line_length = 65536
managesieve_implementation_string = Dovecot Pigeonhole
managesieve_max_compile_errors = 5
}

dict {
quotadict = mysql:/etc/dovecot/dovecot-dict-quota.conf
}

plugin {
quota = dict:user::proxy::quotadict
acl = vfile:/etc/dovecot/acls
trash = /etc/dovecot/trash.conf
sieve_global_path = /var/sieve/globalfilter.sieve
sieve_before = /var/sieve/globalfilter.sieve
sieve = ~/dovecot.sieve
sieve_dir = ~/sieve
sieve_global_dir = /var/sieve/
#sieve_extensions = +notify +imapflags
sieve_max_script_size = 1M
#sieve_max_actions = 32
#sieve_max_redirects = 4
}

namespace inbox {
inbox = yes

mailbox Trash {
auto = subscribe
special_use = \Trash
autoexpunge = 30d
}
mailbox Drafts {
auto = subscribe
special_use = \Drafts
}
mailbox Sent {
auto = subscribe
special_use = \Sent
}
mailbox Spam {
auto = subscribe
special_use = \Junk
autoexpunge = 30d
}

}

log_path = /var/log/dovecot.log
info_log_path = /var/log/dovecot-info.log
debug_log_path = /var/log/dovecot-debug.log
!include_try /etc/dovecot/sni.conf

Any idea?