GS1915-8EP verliert Verbindung zum NCC

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RenéG
RenéG Posts: 5
First Comment

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: 1,639  Zyxel Employee
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    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
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    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: 1,639  Zyxel Employee
    First Anniversary 10 Comments Friend Collector First Answer
    edited June 2023
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    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
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    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: 1,639  Zyxel Employee
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    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
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    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: 1,639  Zyxel Employee
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    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
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    Thank you very much, I think that solved my problem.
    What do you mean by "illegal DHCP server"?

  • Zyxel_Melen
    Zyxel_Melen Posts: 1,639  Zyxel Employee
    First Anniversary 10 Comments Friend Collector First Answer
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    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

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