au (KDDI) slow internet in Japan: tests, evidence and complaints

If your au (KDDI) connection is slow or unreliable, start with these equipment checks. Then document a repeatable result and ask for a specific investigation.

Applies to: Paths checked in NEC Platforms’ BL3000HM 機能詳細ガイド (feature guide), linked from the BL3000HM manual, and on au.com. The BL1500HM uses the same address and login; its guide puts UPnP directly under ネットワーク設定 › UPnP設定.Checked: 3 November 2026

When this helps

  • You use au (KDDI) in Japan.
  • Your connection is slower than expected, drops out or performs badly at certain times.

Check your auひかり ホームゲートウェイ

These checks apply to auひかり ホームゲートウェイ. Check the model before following its menus.

  1. Open 基本情報 (Basic info) for the lights, firmware, WAN address, DNS servers and Wi-Fi channels in use.

  2. Open ネットワーク診断 › ログの表示 (Show log) for the device log; ファイルへ保存 (Save to file) downloads it.

  3. ホームゲートウェイ詳細設定 › 4.メンテナンス › PINGテスト (Ping test) checks whether an address answers from the gateway.

Separate the service from your home Wi-Fi

For the exact settings and supported equipment, see the auひかり ホームゲートウェイ guide.

Do not factory-reset the equipment as a first step. A reset can erase service settings and interrupt phone service.

  1. Compare a wired connection to the router with Wi-Fi on the same device.

  2. Repeat the same test server during the slowdown and at a quieter time.

  3. Record download, upload, latency and whether another household device was using the connection.

How to complain to au (KDDI)

Use au (KDDI)’s official support to report the fault. Request a formal complaint reference if it remains unresolved.

Include the plan wording, dates, test conditions, previous references and the specific outcome you want. Ask for a written response.

Check the complaints procedure in your Japan service contract before escalating. Use the national regulator’s consumer guidance for your service.

Collect the evidence with Kilobat

On a Mac, Kilobat can record connection checks and produce a support report. Review the report and add your test conditions before sharing.

The basic report export is free. Kilobat Pro’s complaint wizard helps assemble your evidence, impact and requested resolution into a draft you review and send.

Measurements cover this Mac while monitoring ran. They cannot prove whole-home uptime, establish provider fault or replace a required official measurement procedure.

Sources

Checked on 3 November 2026.