# Response Codes

Below are the most common response codes you may encounter while using PlainProxies IPv6 Proxies and how to resolve them.

<table><thead><tr><th width="310">Response</th><th>Description</th></tr></thead><tbody><tr><td><strong>407 – Proxy Authentication Required</strong></td><td>User credentials are missing or incorrect, or the connection is coming from an IP that is not whitelisted.</td></tr><tr><td><strong>429 – Too Many Requests</strong></td><td>The user has reached the thread or concurrent connection limit.</td></tr><tr><td><strong>500 – Internal Server Error</strong></td><td>A temporary issue occurred on our server. Please try again later.</td></tr><tr><td><strong>503 – Service Unavailable</strong></td><td>Failed to connect to the target server. DNS resolution failed or the target is unavailable.</td></tr><tr><td><strong>504 – Gateway Timeout</strong></td><td>The proxy server timed out while waiting for a response from the target server.</td></tr></tbody></table>

Certain websites enforce strict rate limits and anti-bot rules.\
When this happens, blocks or limitations come from the target site itself, not from the proxy service.


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# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://docs.plainproxies.com/proxies/ipv6-proxies/response-codes.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.