I refered Linux Dialin Server Setup Guide - Josh Gentry, and do step by step. When I dial up a Window machine into Linux server (have Domain controler) then they only connect about 0.1 mininute. After that, I open files message, mgetty* in /var/log/ directory, I looked errors following:

In message file:

Apr 2 16:50:03 LinuxServer init: cannot execute "/sbin/mgetty-x"
Apr 2 16:50:03 LinuxServer last message repeated 9 times
Apr 2 16:50:03 LinuxServer init: Id "S1" respawning too fast: disabled for 5 minutes
Apr 2 16:55:04 LinuxServer init: cannot execute "/sbin/mgetty-x"
Apr 2 16:55:04 LinuxServer last message repeated 9 times
Apr 2 16:55:04 LinuxServer init: Id "S1" respawning too fast: disabled for 5 minutes

In mgetty.log.ttyS1

04/03 02:25:37 yS1 mgetty: experimental test release 1.1.30-Dec16
04/03 02:25:37 yS1 check for lockfiles
04/03 02:25:37 yS1 checklock: stat failed, no file
04/03 02:25:37 yS1 locking the line
04/03 02:25:37 yS1 makelock(ttyS1) called
04/03 02:25:37 yS1 do_makelock: lock='/var/lock/LCK..ttyS1'
04/03 02:25:37 yS1 lock made
04/03 02:25:37 yS1 tio_get_rs232_lines: status: RTS CTS DSR DTR
04/03 02:25:37 yS1 lowering DTR to reset Modem
04/03 02:25:38 yS1 tss: set speed to 115200 (10002)
04/03 02:25:38 yS1 tio_set_flow_control( HARD )
04/03 02:25:38 yS1 waiting for line to clear (VTIME), read:
04/03 02:25:38 yS1 send: AT&F1M0[0d]
04/03 02:25:38 yS1 waiting for line to clear (VTIME), read: AT&F1M0[0d][0d][0a]OK[0d][0a]
04/03 02:25:39 yS1 removing lock file
04/03 02:25:39 yS1 waiting...
04/03 02:55:39 yS1 select returned 0
04/03 02:55:39 yS1 checking if modem is still alive
04/03 02:55:39 yS1 makelock(ttyS1) called
04/03 02:55:39 yS1 do_makelock: lock='/var/lock/LCK..ttyS1'
04/03 02:55:39 yS1 lock made
04/03 02:55:39 yS1 mdm_send: 'AT'
04/03 02:55:39 yS1 got:AT[0d]
04/03 02:55:39 yS1 mdm_command: string 'AT'
04/03 02:55:39 yS1 got:[0d][0a]OK[0d]
04/03 02:55:39 yS1 mdm_command: string 'OK' -> OK
04/03 02:55:39 yS1 waiting for line to clear (VTIME), read:
04/03 02:55:39 yS1 removing lock file
04/03 02:55:39 yS1 waiting...
04/03 03:25:39 yS1 select returned 0
04/03 03:25:39 yS1 checking if modem is still alive
04/03 03:25:39 yS1 makelock(ttyS1) called
04/03 03:25:39 yS1 do_makelock: lock='/var/lock/LCK..ttyS1'
04/03 03:25:39 yS1 lock made
04/03 03:25:39 yS1 mdm_send: 'AT'
04/03 03:25:39 yS1 got:[0a]AT[0d]
04/03 03:25:39 yS1 mdm_command: string 'AT'
04/03 03:25:39 yS1 got:[0d][0a]OK[0d]
04/03 03:25:39 yS1 mdm_command: string 'OK' -> OK
04/03 03:25:39 yS1 waiting for line to clear (VTIME), read:
04/03 03:25:40 yS1 removing lock file
04/03 03:25:40 yS1 waiting...
04/03 03:55:40 yS1 select returned 0
04/03 03:55:40 yS1 checking if modem is still alive
04/03 03:55:40 yS1 makelock(ttyS1) called
04/03 03:55:40 yS1 do_makelock: lock='/var/lock/LCK..ttyS1'
04/03 03:55:40 yS1 lock made
04/03 03:55:40 yS1 mdm_send: 'AT'
04/03 03:55:40 yS1 got:[0a]AT[0d]
04/03 03:55:40 yS1 mdm_command: string 'AT'
04/03 03:55:40 yS1 got:[0d][0a]OK[0d]
04/03 03:55:40 yS1 mdm_command: string 'OK' -> OK
04/03 03:55:40 yS1 waiting for line to clear (VTIME), read:
04/03 03:55:40 yS1 removing lock file
04/03 03:55:40 yS1 waiting...
04/03 04:25:40 yS1 select returned 0
04/03 04:25:40 yS1 checking if modem is still alive
04/03 04:25:40 yS1 makelock(ttyS1) called
04/03 04:25:40 yS1 do_makelock: lock='/var/lock/LCK..ttyS1'
04/03 04:25:40 yS1 lock made
04/03 04:25:40 yS1 mdm_send: 'AT'
04/03 04:25:40 yS1 got:[0a]AT[0d]
04/03 04:25:40 yS1 mdm_command: string 'AT'
04/03 04:25:40 yS1 got:[0d][0a]OK[0d]
04/03 04:25:40 yS1 mdm_command: string 'OK' -> OK
04/03 04:25:40 yS1 waiting for line to clear (VTIME), read:
04/03 04:25:41 yS1 removing lock file
04/03 04:25:41 yS1 waiting...
04/03 04:55:41 yS1 select returned 0
04/03 04:55:41 yS1 checking if modem is still alive
04/03 04:55:41 yS1 makelock(ttyS1) called
04/03 04:55:41 yS1 do_makelock: lock='/var/lock/LCK..ttyS1'
04/03 04:55:41 yS1 lock made
04/03 04:55:41 yS1 mdm_send: 'AT'
04/03 04:55:41 yS1 got:[0a]AT[0d]
04/03 04:55:41 yS1 mdm_command: string 'AT'
04/03 04:55:41 yS1 got:[0d][0a]OK[0d]
04/03 04:55:41 yS1 mdm_command: string 'OK' -> OK
04/03 04:55:41 yS1 waiting for line to clear (VTIME), read:
04/03 04:55:41 yS1 removing lock file
04/03 04:55:41 yS1 waiting...
I know that some settings configuration error, but I can't find them.
Somebody met this error, help me please. Thanhk you very much!

Please don't use the Member Intro forum to ask technical questions. Posting your threads in the correct forum will mean that the correct audience sees your question.

Moved to Linux-Networking.