GS1915-8EP verliert Verbindung zum NCC

RenéG
RenéG Posts: 5
First Comment
in Nebula

Hallo zusammen,

ich habe mir einen GS1915-8EP für ein kleines Netzwerk-Projekt zugelet. Diesen habe ich an meinen Router (192.168.1.1) angeschlossen und ihn im NCC regestriert und per DHCP eine Adresse zuweisen lassen (192.168.1.239). Bis dahin lief aller ohne Probleme. Bis ich in den Einstellungen im Router die Subnetzmaske verändert habe (von ursprünglich 255.255.255.0 auf 255.255.0.0). Zunächst hatte der Switch damit keine Probleme und hat die Einstellung auch übernommen. Sprich, ich habe mich mit dem Laptop auf ein Port gesteckt und habe in der Eingabeaufforderung "ipconfig" eingegeben. Dort wurde mir die neue Subnetzmaske angezeigt. Auch als ich dem Laptop eine feste IP gegeben habe (192.168.2.7) hatte ich keine Probleme.

Für mich als neuling in der IT (😅) war damit alles in ordung.

In der daurauffolgenden Nacht hatte der Switch allerdings offensichtlich die Verbindung zum NCC verloren. Was mich verwundert hatte, war das der am Switch angeschlossene AP jedoch noch Online war und ich über das Wlan ganz normal online gehen konnte. Auch am Port des Switches konnte ich mich aufstecken und online gehen (Sowohl mit dynamischer als auch Statischer IP). Einfaches Neustarten konnte das Problem leider nicht lösen. Erst als ich die Subnetzmaske im Router wieder auf 255.255.255.0 geändert hatte und den Switch neu gestartet habe, wurde er mir wieder als Online angezeigt.

Der Support konnte mir bisher leider noch nicht helfen, deshalb hoffe ich auf leicht verständliche Antworten von euch erfahrenen Nutzern😄

Beste Grüße

René

All Replies

  • Zyxel_Melen
    Zyxel_Melen Posts: 2,638  Zyxel Employee
    Zyxel Certified Network Engineer Level 1 - Switch Zyxel Certified Network Administrator - Switch Zyxel Certified Network Administrator - Nebula Zyxel Certified Sales Associate

    Hi @RenéG,

    When the switch is offline, it is still forwarding traffic so your AP can be online. Besides, changing the subnet mask won't cause your switch to go offline. It goes offline might be due to another problem.

    May I know when did this occur? And could you help to change the subnet mask to 255.255.0.0 and enable Zyxel support for me to check?

    Please go to Help (On the top right) > Support Request > Zyxel support Access to enable and save.

    Zyxel Melen


  • RenéG
    RenéG Posts: 5
    First Comment
    edited May 2023

    The first time I changed the subnet mask was on 27 May. The following night the switch went offiline for the first time. On 28 May, I set the subnet mask back to 255.255.255.0, after which the switch went online again. So I changed the mask directly again and in the following night it went offline again. So I set the mask on 29 May again to 255.255.255.0 and left it like that since then.

    Currently I am not on site, so I can not change the subnet mask. As soon as I have changed it, I will let you know.
    The Zyxel support access is already enabled, do you need any data or links from me?

  • Zyxel_Melen
    Zyxel_Melen Posts: 2,638  Zyxel Employee
    Zyxel Certified Network Engineer Level 1 - Switch Zyxel Certified Network Administrator - Switch Zyxel Certified Network Administrator - Nebula Zyxel Certified Sales Associate
    edited June 2023

    Hi @RenéG,

    Thanks for the privilege.

    I checked the event log but I couldn't find what caused your switch offline from 5/27 to 5/29.

    But I also found that GS1915 disconnects again on 06/01 at 02:11, which occurred after you changed back to DHCP IP. Could you help me to log in to GS1915 and collect the tech support file for me to check? The login password you can find in Site-wide > Configure > Site settings > Device Configuration.

    Zyxel Melen


  • RenéG
    RenéG Posts: 5
    First Comment

    After the Switch went offline again last night, I was briefly on site again this morning. I set the subnet mask in the router to 255.255.255.0 for a short time so that the switch would connect again and then set it back to 255.255.0.0. The switch is now online again. I have sent you the password as a message.

  • Zyxel_Melen
    Zyxel_Melen Posts: 2,638  Zyxel Employee
    Zyxel Certified Network Engineer Level 1 - Switch Zyxel Certified Network Administrator - Switch Zyxel Certified Network Administrator - Nebula Zyxel Certified Sales Associate

    Hi @RenéG,

    I checked the tech support and found the disconnect was due to getting the wrong DHCP IP address.

    When the switch is offline, it gets the DHCP IP address: DHCP(192.168.3.121/24), gateway(192.168.3.1), and DNS(192.168.3.1). This looks not the correct gateway IP, right?

    In order to make sure the switch is online, you can consider setting static IP as you mentioned before, which won't cause the switch to be offline.

    Zyxel Melen


  • RenéG
    RenéG Posts: 5
    First Comment

    Alright, I have now given the switch a Static IP address (192.168.1.217, Gateway: 192.168.1.1, Primary DNS: 8.8.8.8, Secondary DNS: 192.168.1.1). The switch is back online with these settings for now, I hope that it does not go offline again after a few hours.

    The AP that is connected to the switch now has problems connecting to the NCC. I assume that I have to set the same settings for the AP?

  • Zyxel_Melen
    Zyxel_Melen Posts: 2,638  Zyxel Employee
    Zyxel Certified Network Engineer Level 1 - Switch Zyxel Certified Network Administrator - Switch Zyxel Certified Network Administrator - Nebula Zyxel Certified Sales Associate

    Hi @RenéG,

    Yes, you can change from DHCP to static IP to verify.

    By the way, to make sure your client won't get the wrong DHCP IP address, I suggest finding out the illegal DHCP server

    Zyxel Melen


  • RenéG
    RenéG Posts: 5
    First Comment

    Thank you very much, I think that solved my problem.
    What do you mean by "illegal DHCP server"?

  • Zyxel_Melen
    Zyxel_Melen Posts: 2,638  Zyxel Employee
    Zyxel Certified Network Engineer Level 1 - Switch Zyxel Certified Network Administrator - Switch Zyxel Certified Network Administrator - Nebula Zyxel Certified Sales Associate

    Hi @RenéG,

    The illegal DHCP server is an untrusted DHCP server that will provide the wrong DHCP IP addresses, such as incorrect DNS server settings or default gateways, redirecting network traffic to unauthorized destinations. This causes the clients cannot access the Internet or security issues.

    Zyxel Melen


  • MartinTat
    MartinTat Posts: 5  Freshman Member
    First Comment Third Anniversary

    I already had the problem several times and currently again acutely that some switches (GS1915, XMG1915, GS1920) often or currently do not connect to Nebula NCC. Devices on the switches, including APs, always connect to NCC. Some APs are switched off at night or when not present in the living area, but are immediately reconnected online with NCC. I have also not noticed any other restrictions with regard to the Internet or IPTV etc. With regard to NCC diagnostics, however, I have noticed that http://portquiz.net:6667/ or http://portquiz.net:4335 cannot be accessed. But other pings like listed in the community 34.243.116.158, 34.246.20.161, 52.16.90.243 or d.nebula.zyxel.com or 1.1.1.1 etc. are working.
    I have also often noticed that I can always add new switches to the organization with the app, for example, and they then appear immediately in NCC. However, after parameterization and then de-energizing and placing in the desired position in the house, the device is not or never again online in NCC. However, the function should always be correct as devices behind it with VLANs work correctly.
    I have now been able to solve the problem in the following way. Connect to the switch with web browser via assigned DHCP or DHCP via static list and write IP 1.1.1.1 in the empty field Domain Name Server - Preference1 on the switch. The switch is online in NCC within 20 seconds and can be parameterized again via NCC.

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