diff --git a/docs/ikev2-howto-zh.md b/docs/ikev2-howto-zh.md
index 7b3d32f..ecbe753 100644
--- a/docs/ikev2-howto-zh.md
+++ b/docs/ikev2-howto-zh.md
@@ -504,12 +504,14 @@ wget https://git.io/ikev2setup -O ikev2.sh && sudo bash ikev2.sh --auto
    Ubuntu 18.04 上的 NSS 问题的解决方法
    </summary>
 
+   **注：** 该解决方法仅适用于运行在 `x86_64` 架构下的 Ubuntu 18.04 系统。
+
    首先安装更新版本的 `libnss3` 相关的软件包：
 
    ```
-   wget http://security.ubuntu.com/ubuntu/pool/main/n/nss/libnss3_3.49.1-1ubuntu1.5_amd64.deb
-   wget http://security.ubuntu.com/ubuntu/pool/main/n/nss/libnss3-dev_3.49.1-1ubuntu1.5_amd64.deb
-   wget http://security.ubuntu.com/ubuntu/pool/universe/n/nss/libnss3-tools_3.49.1-1ubuntu1.5_amd64.deb
+   wget https://mirrors.kernel.org/ubuntu/pool/main/n/nss/libnss3_3.49.1-1ubuntu1.5_amd64.deb
+   wget https://mirrors.kernel.org/ubuntu/pool/main/n/nss/libnss3-dev_3.49.1-1ubuntu1.5_amd64.deb
+   wget https://mirrors.kernel.org/ubuntu/pool/universe/n/nss/libnss3-tools_3.49.1-1ubuntu1.5_amd64.deb
    apt-get -y update
    apt-get -y install "./libnss3_3.49.1-1ubuntu1.5_amd64.deb" \
      "./libnss3-dev_3.49.1-1ubuntu1.5_amd64.deb" \
diff --git a/docs/ikev2-howto.md b/docs/ikev2-howto.md
index 6d8963e..6349e85 100644
--- a/docs/ikev2-howto.md
+++ b/docs/ikev2-howto.md
@@ -504,12 +504,14 @@ Before continuing, you **must** restart the IPsec service. The IKEv2 setup on th
    Workaround for the NSS bug on Ubuntu 18.04
    </summary>
 
+   **Note:** This workaround should only be used on Ubuntu 18.04 systems running on the `x86_64` architecture.
+
    First, install newer versions of `libnss3` related packages:
 
    ```
-   wget http://security.ubuntu.com/ubuntu/pool/main/n/nss/libnss3_3.49.1-1ubuntu1.5_amd64.deb
-   wget http://security.ubuntu.com/ubuntu/pool/main/n/nss/libnss3-dev_3.49.1-1ubuntu1.5_amd64.deb
-   wget http://security.ubuntu.com/ubuntu/pool/universe/n/nss/libnss3-tools_3.49.1-1ubuntu1.5_amd64.deb
+   wget https://mirrors.kernel.org/ubuntu/pool/main/n/nss/libnss3_3.49.1-1ubuntu1.5_amd64.deb
+   wget https://mirrors.kernel.org/ubuntu/pool/main/n/nss/libnss3-dev_3.49.1-1ubuntu1.5_amd64.deb
+   wget https://mirrors.kernel.org/ubuntu/pool/universe/n/nss/libnss3-tools_3.49.1-1ubuntu1.5_amd64.deb
    apt-get -y update
    apt-get -y install "./libnss3_3.49.1-1ubuntu1.5_amd64.deb" \
      "./libnss3-dev_3.49.1-1ubuntu1.5_amd64.deb" \