> Source: [sk1000213](https://support.checkpoint.com/results/sk/sk1000213)

# sk1000213 - Claude AI traffic experiences connectivity issues through the Security Gateway

| Property | Value |
|----------|-------|
| Solution ID | sk1000213 |
| Date Created | 2026-10-01 |
| Last Modified | 2026-10-04 |
| Technical Level | General |
| Products | Security Gateway |
| Versions | R81.20 |
| OS | Gaia |

## Symptoms

- * The `claude.ai` session stops responding without displaying a clear browser-side error message.   
* The issue does not occur when HTTP/2 is disabled in the web browser.
* The time until failure depends on the prompt size and interaction length. Larger prompts or longer sessions trigger the failure sooner.
* Kernel debug logs ( `fw ctl debug -m WS + all` ) contain these entries:   
  ws_http2_parse_frame_window_update: new window size is less than legal values ws_http2_parse_frame_window_update: window size too small during long time. closing connection.

## Cause

An issue in the Check Point Web Security HTTP/2 inspection path on the affected Security Gateway.

During HTTP/2 inspection, the Security Gateway processes a client-side `WINDOW_UPDATE` frame on a stream that is already in the `HALF_CLOSED_CLIENT` state. Because the client side of the stream is closed, the HTTP/2 parser interprets the updated window size as being below the allowed threshold. As a result, the connection is terminated.

## Solution

<br />

[Contact Check Point Support](https://www.checkpoint.com/support-services/contact-support/) to get a Hotfix for this issue.

A Support Engineer will make sure the Hotfix is compatible with your environment before providing it.  
For faster resolution and verification, collect these files:

1. [CPinfo](https://support.checkpoint.com/results/sk/sk92739) file from the Management Server involved in the case.
2. [CPinfo](https://support.checkpoint.com/results/sk/sk92739) file from the Check Point Firewall / each Cluster Member / Security Group involved in the case.

**Hotfix installation instructions:**   
Refer to [sk168597 - How to install a Hotfix](https://support.checkpoint.com/results/sk/sk168597).

<br />

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