# Manage networking and IP addresses

How to change public and private IPv4 on the instance detail page, and why changing the public IPv4 has no confirmation dialog and no way to get the old address back.

The **Network configuration** card on the instance detail page manages two kinds of addresses: public IPv4 and private IPv4. They change in completely different ways — private IPv4 is an address you type in yourself, validated by the backend, while public IPv4 is a single button that has the platform assign a new address from a pool automatically. **Changing the public IPv4 releases the current address immediately, and there is no way to get it back.** Read the next section before you select the button.

_Interface illustration: The Network configuration card on the instance detail page: Primary Public IPv4 field, Change Public IPv4 button, private IPv4 field, and its change entry point_

## Before you begin

> [!CAUTION]
> Selecting **Change Public IPv4** has no confirmation dialog — it runs the
> moment you select it. The old address is released back to the platform's
> shared pool immediately and stops being under your control. There is no "undo"
> or "restore the previous address" feature anywhere in the product.

If the instance has more than one public IPv4 address, one selection replaces **all** of them at once. There is no way to pick a single address to change. Before you select the button, confirm:

- Whether any DNS records pointing at the old address can tolerate a change
- Whether firewall allowlists and third-party systems that reference the old address are documented, so you can update them afterward

There is no limit on how often you can do this, no cooldown period, and no extra charge for it. That does not make it safe to try casually — it just means the platform will not stop an accidental click for you.

## What happens, what does not happen

| What happens                                                                                                                      | What does not happen                                                                                                          |
| --------------------------------------------------------------------------------------------------------------------------------- | ----------------------------------------------------------------------------------------------------------------------------- |
| The request runs immediately, the instance shows a **Replacing IPv4** message, and the platform processes the rest asynchronously | No confirmation dialog appears and you are not asked to type the instance name — selecting the button counts as confirming    |
| The old address is released into the platform's shared pool of idle addresses                                                     | The old address is not held for your account, and there is no cooldown — the next user who requests an address can receive it |
| The platform assigns a new address from the idle pool to the instance                                                             | No "undo" or "restore the previous IP" button or API exists                                                                   |
| If the instance has multiple public IPv4 addresses, this action replaces all of them                                              | Only the address you intended to change is not singled out — the request does not target a specific address                   |

## Change the public IPv4

1. Open the instance detail page and find the **Network configuration** card. Confirm the **Primary Public IPv4** field shows the address you intend to change.
2. On the **Network configuration** card, select **Change Public IPv4**. The action takes effect the moment you select it.
3. A **Replacing IPv4** message appears. Network connectivity is briefly interrupted until the new address is attached.
4. Once the change completes, the **Primary Public IPv4** field shows the new address. Update any DNS records, firewall allowlists, and third-party configuration that referenced the old address — the platform has no way to recover it for you.

_Interface illustration: The Change Public IPv4 button in its clicked state and the following Replacing IPv4 message, showing no confirmation dialog anywhere near the button_

## When the change fails

Changing the public IPv4 runs as two asynchronous steps: release the old address, then attach a new one. If the overall request fails, the platform only reclaims the **unused new address** automatically — it never tries to bring the old address back.

> [!NOTE]
> In the rare case where the failure happens in the window between the old address being released and the new one being attached, the instance can be left without a public IPv4 for a while. The platform does not automatically recover from this — restoring public IPv4 access requires contacting Cypacky Support to manually re-trigger the assignment. Record the work request ID beforehand.

## When the button is unavailable

- **The instance's region does not support public IPv4**: only Hong Kong, Macau, North Korea, Antarctica, and Japan-series instances support it. On other instances, the **Change Public IPv4** button does not appear on the **Network configuration** card at all.
- **The instance state is not Running or Stopped**: for example, during maintenance or while pending provisioning, the button appears but is disabled.
- **Another work request is in progress**: the button stays disabled while a create, rebuild, upgrade, or migration task is pending or running.
- **The account or instance is delinquent, security-locked, or has a pending invoice**: these checks are shared with other instance actions. Refer to the "When an action is rejected" section of [Start, stop, and restart an instance](/compute/instances/management/power/) for the exact messages.

## Change the private IPv4

Changing the private IPv4 works differently from the public one: you type the target address into a form, and the backend validates the subnet range and availability after you submit.

If the address format is invalid, the interface shows:

> Enter a valid IPv4 address.

The form also shows this note below the field:

> The backend performs the final subnet and availability validation.

When the change takes effect depends on whether the instance is currently running. While the instance is running, the interface shows:

> The instance will shut down, change its address, and restart automatically. Network connections will be interrupted temporarily, and existing public IPv4 mappings will be updated.

While the instance is stopped, the interface shows:

> The instance is stopped. It will use the new address on its next start, and existing public IPv4 mappings will be updated.

_Interface illustration: The private IPv4 change form, showing the address input field and the two messages for the running and stopped states_

## Related documentation

- [Instance details](/compute/instances/detail/)
- [Start, stop, and restart an instance](/compute/instances/management/power/)
- [Delete an instance](/compute/instances/management/delete/)
- [Work requests](/compute/operations/work-requests/)