> ## Documentation Index > Fetch the complete documentation index at: https://www.datum.net/docs/llms.txt > Use this file to discover all available pages before exploring further. > ## Agent Instructions > Agent home for Datum, with what it is, pricing, and how to act: https://agents.datum.net > If you can only fetch URLs: read https://www.datum.net/docs/llms.txt in full and open the most specific page for the task. Commands, limits, and field paths are on task, operations, and limits pages, not on section overviews. Pages described as "Documentation is coming soon" are placeholders. > If you have a shell or can save files: download https://www.datum.net/docs/llms-full.txt (every page, about 740 KB) once and search it with grep, instead of fetching pages one at a time. > datumctl describes itself: `datumctl api-resources` lists resource types and `datumctl explain ` shows a schema. To act on live resources, use Datum MCP or datumctl. To search the docs, use the Docs MCP server at https://www.datum.net/docs/mcp. # gVPC troubleshooting > Find out why a gVPC network or Instance address isn't working, and fix common network errors. This page lists common [gVPC](https://www.datum.net/docs/galactic-vpc/overview.md) errors and how to fix them. gVPC is still being built, so this page will grow. > [!NOTE] > > gVPC is in preview, and the `networking.datumapis.com/v1alpha` API can change. Start with `datumctl network describe NETWORK_NAME` or `datumctl network service describe SERVICE_NAME`. Each ends with a diagnosis that names the cause and who needs to act. For more information, see [Operations](https://www.datum.net/docs/galactic-vpc/operations.md). ## Common problems | Error or reason | Meaning | What to do | | - | - | - | | `NetworkNotFound` | The network named in the workload's `networkInterfaces` doesn't exist, so no Instances start. | Create the network. See [Configuration](https://www.datum.net/docs/galactic-vpc/configuration.md#create-a-network). | | `permission to use the network was denied` | You don't have the `networking.datumapis.com/networks.use` permission on the network. | Ask a project administrator for the **Network Admin** role. See [Permissions](https://www.datum.net/docs/galactic-vpc/configuration.md#permissions). | | Instances never start, with `NetworkFailedToCreate` and `has not reached location` | The workload is attached to a network that is being deleted. A network that is being deleted can still report `Ready`. | Run `datumctl get network NETWORK_NAME -o yaml` and check for a `deletionTimestamp`. To see where the network exists, run `datumctl get networkcontexts,networkbindings`. Attach the workload to another network. | | `RangeOccupied` | A network you're deleting still has Instances holding addresses on it. | Delete the workloads attached to the network. See [Delete a network](https://www.datum.net/docs/galactic-vpc/operations.md#delete-a-network). | | A network is rejected for not including IPv6 | `spec.ipFamilies` doesn't include `IPv6`. | Keep the default, `[IPv6]`. | | Connections between locations stall | `spec.mtu` is larger than the default of `1440`. | Keep the default MTU. | | An Instance can't reach a peer | The app listens only on IPv4, or the URL doesn't bracket the IPv6 address. | Listen on `::` and use `http://[ADDRESS]:PORT/`. See [Traffic and connecting](https://www.datum.net/docs/galactic-vpc/networks/traffic.md#connect-to-other-instances). | | `NoMatchingInterfaces`, `MultipleNetworks`, or `NoServingLocations` | A network service isn't serving. | See [Check a network service](https://www.datum.net/docs/galactic-vpc/networks/network-services.md#check-a-network-service). | ## MTU gVPC networks use an MTU of `1440` bytes by default. The [Cloud Portal](https://cloud.datum.net) shows it on a network's **Configuration** tab, and `datumctl get network NETWORK_NAME -o yaml` shows it in `spec.mtu`. The MTU is smaller than the common Ethernet default of `1500`, because Datum wraps each packet in an extra IPv6 header to carry it between locations. See [Segment routing](https://www.datum.net/docs/platform/segment-routing.md). > [!WARNING] > > **Needs further investigation.** How the `1440` MTU affects traffic between Instances hasn't been fully documented yet. If large requests, file transfers, or TLS handshakes between Instances stall while small requests work, packet size is a likely cause: keep the default MTU, and check that the app and any tunnels inside the Instance don't assume `1500`. For an overlay or tunnel between Instances, such as VXLAN, an MTU of `1360` or less has worked in testing. Report what you find to [support@datum.net](mailto:support@datum.net). For problems with the workloads on a network, see [Compute troubleshooting](https://www.datum.net/docs/compute/troubleshooting.md). This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.