GS1900-8 can not get the SNTP function to work

DennizOlof Posts: 20  Freshman Member
edited April 14 in Switch

I have a GS1900-8 switch installed, regular small LAN with no special configuration options enabled, everything beside some of the simple basic things you need to configure to use the Zyxel switch has been changed.

I am on the latest firmware GS1900-8_2.30(AAHH.0)C0

The LAN has a Zyxel USG 60W firewall installed and connected with a fiber connection that has a public IP. The SNTP settings in the firewall works well. I have tried several different servers on the switch but it does not seem to want to set the time. It was also not possible to enter a DNS name as it would not accept it but if I input a IP number I could save the settings.

The problem is it does not seem to work at all, I can set the time on my laptop byt forcing a sync. Other units on the network have no problem pulling data from the same SNTP server.

I think Zyxel need to take a close look at this function in the switch lineup you have as I think this carries over to all the switches. I suspect it might be some compatibility issue with some SNTP servers. I have not tried more than four or five servers, none of them worked. And I find this issue to be important as the time stamping of events is what you need when searching for faults or errors. For me personally I do not mind that the SNTP is not working but it is still irritating, this simple function should work.

Is there a list of tested and verified SNTP servers that works, would be nice with different servers around the world that Zyxel knows works if you do not find anything wrong with the SNTP function.

/Regards Dennis



  • CrazyTacos
    CrazyTacos Posts: 53  Ally Member
    Hello Denniz
    Did you remember to configure a default gateway for the GS1900?
    If your switch can ping then there really shouldn't be a reason why it can't sync with NTP...
  • JasonTsai
    JasonTsai Posts: 104  Zyxel Employee
    Hi @DennizOlof,

    I have tested SNTP with GS1900-8 in my local office and it works well.
    The screenshot below is my configuration.
    (Remember to enable SNTP first because default configuration is disabled.)
    Please also help to verify the default gateway of GS1900-8 is already settled.

    Hope it helps.
  • JasonTsai
    JasonTsai Posts: 104  Zyxel Employee
    Hi @DennizOlof,

    Just want to follow up on this topic.
    Do you verify the SNTP configuration and the default gateway of GS1900-8?
    Please keep us posted to get more support for you.


  • DennizOlof
    DennizOlof Posts: 20  Freshman Member
    Thanks for feedback, I will have to get back to you. As the switch is in a remote location I can not get to it easy, but I will check if I missed out on anything and get back to you with the findings. Also I will provide a list of the NTP servers I could not get working. So that Zyxel can check to see if there is anything special going on or something is wrong on the NTP server side ?

    I assume you do not need to portmap to the switch for NTP to work, all other units, accesspoints, computers etc have no problems to sync against the servers that did not work in the switch.

    I should have the information and post a follow up before april.

  • DennizOlof
    DennizOlof Posts: 20  Freshman Member
    Good news everyone. I have now resolved the issue.

    I did some investigation and I decided to switch over to DHCP instead as I have no specific need for a static configuration. And suddenly the SNTP function worked.

    I did not change firmware or any other setting, only moved the switch over to DHCP. I upgraded to the v2.40 firmware, same SNTP server still worked, switched to another one that I wanted to use instead. No problems. Also once I did switch to DHCP I could enter a hostname for SNTP and it worked fine.


    There is some issue with a static configuration, perhaps the switch can not do a DNS lookup or something else. The strange thing is that even though I switched to DHCP the configuration is still the same as with static configuration. But now SNTP works as it should. Everything else was fine in static mode, or as far as I can tell. So now Zyxel knows about this issue, and everyone else. Use DHCP and you will not have SNTP problems.

    Also note that this issue was with the switch it self, the traffic and units connected to the switch had no issues with anything.

    Firmware seems stable too, had been running for 130 days, no issues from what I can tell.

    /Happy longtime user of zyxel products

  • Zyxel_Ryan
    Zyxel_Ryan Posts: 66  Zyxel Employee
    Hi @DennizOlof

    Thanks for your sharing!
    We are curious about your conclusion because it is not reasonable that the SNTP server only works fine with DHCP. If the DHCP works fine, it should also be fine to work with static IP. 
    Could you please follow steps below to do some test so that we can clarify what might be the problem? 

    1. When DHCP works fine with SNTP server, remember the settings (IP, Subnet mask, GW, DNS). (Monitor>System>IP)
    2. Use the same settings on static IP settings. (Configuration>System>IP) 
    3. Try to ping by Maintenance> Diagnostic> PING. If ping test is worked, it should be fine to sync NTP server as well.

    4. If ping works fine but the SNTP still cannot work, please give us your SNTP server address so that we can reproduce it on local site. 


  • newBie_
    newBie_ Posts: 9  Freshman Member
    I encountered this problem before.
    The solution is same as @Ryan 's suggestion.
    The problem came out to be my mis-setting of DNS server. :P

  • Dudley_Winchester
    Dudley_Winchester Posts: 21  Freshman Member
    I get the same problem. When using Static IP and even having DNS1 & 2 as, (Google DNS) and I try to use a hostname, Chrome just shows "waiting for" and it will never save a domain NTP address such as
    As I would prefer to have my switch addresses static than have accurate time, I'm hoping ZyXEL will look into this as a bug. On the GS1920, you can't even use hostnames for NTP which is far worse! The big NTP players such as really don't like IP addresses being used.
  • Zyxel_Ryan
    Zyxel_Ryan Posts: 66  Zyxel Employee
    Hi @Dudley_Winchester

    I did a test with my GS1900-8 (V2.40(AAHH.1)C0) based on your setting in the description, but everything works fine. I can ping NTP server ( and sync time with SNTP normally. 
    Please refer below.

    Static IP setting:

    Ping NTP server:

    I can use domain name in SNTP server: 

    Can you also do the same test? If you still have problem, please screenshot your results for us so that we can clarify the problem?

    Furthermore, I also tried to use domain name setting in NTP server setting on GS1920-24, but everything also works fine below.

    Do you mean that you cannot use domain name to sync time? If yes, please also check DNS server are set so that switch can resolve domain name. (Basic Setting>DNS)

  • Dudley_Winchester
    Dudley_Winchester Posts: 21  Freshman Member
    Hi ZyXEL_Ryan,
    Apologies for the slow response; I was gathering info from multiple customer sites.
    The GS1920-24 all looks happy and I tested with V4.50 firmware... very happy!
    I'm having problems still on the GS1900-8 using FW 2.40. It does seem to be DNS related though.
    I've tried both the USG Firewall IP for DNS1 and Google, but cannot ping from switch to I think if I can crack that one I will get NTP working.
    Oddly I cannot even ping the gateway IP, so it's not a DNS problem (I think) - but I can ping the gateway from my laptop.
    I'm using STP and seeing many topology changes, so I think I need to look at this before making it look like a NTP problem.
    ~ Dudley