[FS#260] ntp server doesn't work - no reply to clients

[LEDE Bugs]

A new Flyspray task has been opened.  Details are below. 

User who did this - juanriccio (juanriccio) 

Attached to Project - LEDE Project
Summary - ntp server doesn't work - no reply to clients
Task Type - Bug Report
Category - Base system
Status - Unconfirmed
Assigned To - 
Operating System - All
Severity - Low
Priority - Very Low
Reported Version - Trunk
Due in Version - Undecided
Due Date - Undecided
Details - Lede r1735.
I have ntp client and server enabled in LuCi, and my /etc/config/system file has it enabled too, as expected.

 config timeserver 'ntp'
        list server 'openwrt.pool.ntp.org'
        list server 'time.nist.gov'
        option enable_server '1'


The process is indeed active:

~# ps | grep ntp
 2652 root      1176 S    /usr/sbin/ntpd -n -N -l -S /usr/sbin/ntpd-hotplug -p
 4226 root      1176 S    grep ntp

However, no device in my LAN is able to get the time from this server.
Such devices include:
- several IP security cams
- a security NVR
- several desktop computers, most running windows. Suspecting something broken in the Windows default NTP client, I also downloaded an external NTP client utility for testing (NetTime at www.timesynctool.com). That doesn't work, either.

The only possibility I see left is that there is some problem in the Lede system.

More information can be found at the following URL:
https://bugs.lede-project.org/index.php?do=details&task_id=260