NBG-418N v2 time server not working

Erim

I use my NBG-418N v2 in router mode. I set the time server in auto mode, it does not sync the time. I tried other time servers as well but could not succeed. Could you pls tell me why?
I already did a factory-reset the device before to set in router mode... firmware is the latest which is V1.00(AARP.10)C0

ikubuf

Are you using AP mode or router mode?
As I know, NBG418Nv2 in AP mode cannot set gateway information to synchronize time zone with the NTP server. So, you need to synchronize time manually after reboot.

Erim

Router mode... (I am aware that in the AP Mode there is no time sync option available)

ikubuf

Are using Windows OS?
If so, you can open cmd on your laptop/PC and ping to NTP server pool.ntp.org, is it available?
And try with nslookup pool.ntp.org, what is the result of it?

Erim

I use Mac OS. pool.ntp.org server is working and reachable properly. Here is the ping result:

Last login: Wed Oct 26 13:10:55 on ttys000

Erim-MacBook-Pro:~ erimkefeli$ ping pool.ntp.org

PING pool.ntp.org (85.90.244.165): 56 data bytes

64 bytes from 85.90.244.165: icmp_seq=0 ttl=51 time=44.169 ms

64 bytes from 85.90.244.165: icmp_seq=1 ttl=51 time=46.561 ms

64 bytes from 85.90.244.165: icmp_seq=2 ttl=51 time=43.858 ms

64 bytes from 85.90.244.165: icmp_seq=3 ttl=51 time=43.909 ms

64 bytes from 85.90.244.165: icmp_seq=4 ttl=51 time=44.127 ms

ikubuf

I think directly checking the packet on the wan of NBG418n-V2 device is easier to know what happens in your network. 
If the device has sent out the NTP request to the server, but do not receive any response, the issue might be on the NTP server site. If the device do not even sent NTP packet, then it should be the issue on the device.