Update docs

- When uninstalling the VPN, remove the two TCP BBR related lines
  from /etc/sysctl.conf, if they were added during VPN setup.

README-zh.md

@@ -12,7 +12,7 @@ IPsec VPN 可以加密你的网络流量，以防止在通过因特网传送时
 
 ## 快速开始
 
-首先，在你的 Linux 服务器\* 上全新安装 Ubuntu, Debian 或者 CentOS。
+首先，在你的 Linux 服务器\* 上安装 Ubuntu, Debian 或者 CentOS。
 
 使用以下命令快速搭建 IPsec VPN 服务器：
 
@@ -68,7 +68,7 @@ https://gitlab.com/hwdsl2/setup-ipsec-vpn/-/raw/master/vpnsetup.sh
 
 ## 系统要求
 
-一个云服务器，虚拟专用服务器 (VPS) 或者专用服务器，全新安装以下操作系统之一：
+一个云服务器，虚拟专用服务器 (VPS) 或者专用服务器，安装以下操作系统之一：
 
 - Ubuntu 22.04, 20.04 或者 18.04
 - Debian 11 或者 10

README.md

@@ -12,7 +12,7 @@ We will use [Libreswan](https://libreswan.org/) as the IPsec server, and [xl2tpd
 
 ## Quick start
 
-First, prepare your Linux server\* with a fresh install of Ubuntu, Debian or CentOS.
+First, prepare your Linux server\* with an install of Ubuntu, Debian or CentOS.
 
 Use this one-liner to set up an IPsec VPN server:
 
@@ -68,7 +68,7 @@ A pre-built [Docker image](https://github.com/hwdsl2/docker-ipsec-vpn-server) is
 
 ## Requirements
 
-A cloud server, virtual private server (VPS) or dedicated server, freshly installed with:
+A cloud server, virtual private server (VPS) or dedicated server, with an install of:
 
 - Ubuntu 22.04, 20.04 or 18.04
 - Debian 11 or 10

docs/ikev2-howto-zh.md

@@ -52,7 +52,7 @@ Libreswan 支持通过使用 RSA 签名算法的 X.509 Machine Certificates 来
 
 #### 自动导入配置
 
-[**屏幕录影：** 自动导入 IKEv2 配置（支持者）](https://ko-fi.com/post/IKEv2-Auto-Import-Configuration-on-Windows-8-10-a-K3K1DQCHW)
+[**屏幕录影：** 在 Windows 上自动导入 IKEv2 配置](https://ko-fi.com/post/IKEv2-Auto-Import-Configuration-on-Windows-8-10-a-K3K1DQCHW)
 
 **Windows 8, 10 和 11** 用户可以自动导入 IKEv2 配置：
 
@@ -67,7 +67,7 @@ Libreswan 支持通过使用 RSA 签名算法的 X.509 Machine Certificates 来
 
 #### 手动导入配置
 
-[**屏幕录影：** 手动导入 IKEv2 配置（支持者）](https://ko-fi.com/post/Video-IKEv2-Manually-Import-Configuration-H2H1DS8SV)
+[**屏幕录影：** 在 Windows 上手动导入 IKEv2 配置（支持者）](https://ko-fi.com/post/Video-IKEv2-Manually-Import-Configuration-H2H1DS8SV)
 
 或者，**Windows 7, 8, 10 和 11** 用户可以手动导入 IKEv2 配置：
 

docs/ikev2-howto.md

@@ -52,7 +52,7 @@ In certain circumstances, you may need to change the IKEv2 server address. For e
 
 #### Auto-import configuration
 
-[**Screencast:** IKEv2 Auto Import Configuration (supporters)](https://ko-fi.com/post/IKEv2-Auto-Import-Configuration-on-Windows-8-10-a-K3K1DQCHW)
+[**Screencast:** IKEv2 Auto Import Configuration on Windows](https://ko-fi.com/post/IKEv2-Auto-Import-Configuration-on-Windows-8-10-a-K3K1DQCHW)
 
 **Windows 8, 10 and 11** users can automatically import IKEv2 configuration:
 
@@ -67,7 +67,7 @@ If you get an error when trying to connect, see [Troubleshooting](#troubleshooti
 
 #### Manually import configuration
 
-[**Screencast:** IKEv2 Manually Import Configuration (supporters)](https://ko-fi.com/post/Video-IKEv2-Manually-Import-Configuration-H2H1DS8SV)
+[**Screencast:** IKEv2 Manually Import Configuration on Windows (supporters)](https://ko-fi.com/post/Video-IKEv2-Manually-Import-Configuration-H2H1DS8SV)
 
 Alternatively, **Windows 7, 8, 10 and 11** users can manually import IKEv2 configuration:
 

extras/vpnuninstall.sh

@@ -184,10 +184,17 @@ update_sysctl() {
   if grep -qs "hwdsl2 VPN script" /etc/sysctl.conf; then
     bigecho "Updating sysctl settings..."
     conf_bk "/etc/sysctl.conf"
+    count=17
+    line1=$(grep -A 18 "hwdsl2 VPN script" /etc/sysctl.conf | tail -n 1)
+    line2=$(grep -A 19 "hwdsl2 VPN script" /etc/sysctl.conf | tail -n 1)
+    if [ "$line1" = "net.core.default_qdisc = fq" ] \
+      && [ "$line2" = "net.ipv4.tcp_congestion_control = bbr" ]; then
+        count=19
+    fi
     if [ "$os_type" = "alpine" ]; then
-      sed -i '/# Added by hwdsl2 VPN script/,+17d' /etc/sysctl.conf
+      sed -i "/# Added by hwdsl2 VPN script/,+${count}d" /etc/sysctl.conf
     else
-      sed --follow-symlinks -i '/# Added by hwdsl2 VPN script/,+17d' /etc/sysctl.conf
+      sed --follow-symlinks -i "/# Added by hwdsl2 VPN script/,+${count}d" /etc/sysctl.conf
     fi
     if [ ! -f /usr/bin/wg-quick ] && [ ! -f /usr/sbin/openvpn ]; then
       echo 0 > /proc/sys/net/ipv4/ip_forward