How to fix decreased internet speed when connected to SonicWall Global VPN Client

Russell Brown 0 Reputation points
2026-09-29T15:54:29.07+00:00

My internet download speed reduces from over 300Mbps to around 1Mbps when connected to the Global vpn client using windows 11 on my desktop pc. Upload speed remains high with no affect.

Windows for home | Windows 11 | Internet and connectivity
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  1. David-M 127.3K Reputation points Independent Advisor
    2026-09-29T16:38:06.3366667+00:00

    Hi. I'm David, and I'm happy to help you.

    This issue on Windows 11 with SonicWall is frequently caused by a conflict with Receive Segment Coalescing (RSC) on physical network adapters.

    To provide the exact fix for your network card, please follow these steps and reply with a screenshot of the result:

    1. Press "Windows + X" and select "Terminal (Admin)";
    2. Type or paste the following command and press Enter:
    Get-NetAdapter
    1. Take a screenshot of the result and share it here. Use the shortcut "Windows + Shift + S" to use the screenshot tool.

    Looking forward to your reply.

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  2. AI answer

    2026-09-29T15:54:41.9433333+00:00

    A VPN is a known cause of slow connection speed. For Windows 11, the most direct checks are:

    1. Test without the VPN to confirm the slowdown is caused by the VPN path.
    2. If the slowdown happens only when the VPN is on, review the VPN settings and configuration so the connection is passed through correctly and not routed to distant regions or routed incorrectly.
    3. If the PC is on Wi‑Fi, switch to a wired connection if possible. Wired connections are recommended for better transfer speed.
    4. Avoid other apps or background activity that use bandwidth while connected to the VPN.
    5. If the issue happens only on one network, check whether a firewall on that network is limiting traffic.
    6. If the issue happens only with one internet provider, contact the ISP to check whether it is limiting VPN-related traffic.
    7. If general Windows networking remains abnormal after testing, use Network reset only as a last step:
      • Start > Settings > Network & internet > Advanced network settings > Network reset
      • Select Reset now > Yes
      • Restart the PC

    Note: Network reset removes and reinstalls network adapters and resets their settings to default. VPN client software might need to be reinstalled or set up again afterward.

    References:

    AI-generated content may be incorrect. Read our transparency notes for more information.

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