All my zyxel devices shows offline in app and ncc

Andlan58

everything works, I have nebula firewall, two switches and three accesspoints. But since a couple of weeks back all devices shows offline and one ap and one switch is red!

Zyxel_Tina

Hi @Andlan58,

Welcome to the Zyxel Community!

Before troubleshooting, could you first clarify:

When you say the devices are "offline," do you mean they show as offline/red in the Nebula app or NCC dashboard only (while devices behind them still have internet access), or is the entire network actually down and no internet access?

1. Internet connection

• If your entire network has no internet access, please check whether your ISP modem/ONT is functioning normally. This suggests the issue may be on the ISP side.
• If your network does have internet access, but devices still show offline/red in NCC: this points to a cloud connectivity issue (e.g., blocked ports, DNS, or firewall rules) — please continue with the checks below.

2. Firewall rules / network configuration

• Newly added rules may be blocking communication between your devices and Nebula. Devices require outbound access via TCP ports 4335 and 6667 to connect to the cloud, and TCP port 443 for firmware updates.
• Please also check with your ISP to confirm whether there have been any changes to their service or network policies.

3. DNS resolution

• As a test, temporarily change your DNS server to a public DNS service such as Google (8.8.8.8) or Cloudflare (1.1.1.1), and check whether connectivity is restored.

4. Power cycle the affected devices

• If possible, power cycle the offline devices. Starting with the firewall, followed by switches and APs, and check whether they reconnect to NCC afterward.

Additionally, kindly refer to this article for possible reasons why a Nebula device may appear offline.

If the issue persists after these checks, please provide the following information so we can investigate further:

• Device information: Nebula Organization/Site name, affected device models, and current firmware versions
• Network environment: A brief description or diagram of your network topology
• Recent changes: Any recent ISP equipment replacement or configuration modifications
• Zyxel Support Access: Please enable Zyxel Support Access so we can review the device and connection status from our side