Update docs

Author: hwdsl2

docs/advanced-usage-zh.md

@@ -262,7 +262,7 @@ sh vpn.sh
 
 如果你的 VPN 服务器拥有公共（全局单播）IPv6 地址并且满足以下要求，IKEv2 客户端的 IPv6 支持将在 VPN 安装时自动启用，无需手动配置。
 
-**注：** 在 Android 上使用 strongSwan VPN 客户端时，IPv6 无需额外配置即可正常工作。对于 Windows 和 macOS 客户端，请按照以下平台特定步骤进行配置。iOS 客户端目前不支持通过 IKEv2 VPN 路由 IPv6 流量。
+**注：** 在 Android 上使用 strongSwan VPN 客户端时，IPv6 无需额外配置即可正常工作。对于 Windows 和 macOS 客户端，请按照以下平台特定步骤进行配置。iOS 客户端目前不支持通过 IKEv2 VPN 路由 IPv6 流量；你可以改用 [OpenVPN](https://github.com/hwdsl2/openvpn-install/blob/master/README-zh.md) 或 [WireGuard](https://github.com/hwdsl2/wireguard-install/blob/master/README-zh.md)。
 
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docs/advanced-usage.md

@@ -262,7 +262,7 @@ In the examples above, `VPN_L2TP_LOCAL` is the VPN server's internal IP for IPse
 
 If your VPN server has a public (global unicast) IPv6 address and the requirements below are met, IPv6 support for IKEv2 clients is automatically enabled during VPN setup. No manual configuration is needed.
 
-**Note:** IPv6 works without additional configuration when using the strongSwan VPN client on Android. For Windows and macOS clients, follow the platform-specific steps below. iOS clients do not currently support routing IPv6 traffic through the IKEv2 VPN.
+**Note:** IPv6 works without additional configuration when using the strongSwan VPN client on Android. For Windows and macOS clients, follow the platform-specific steps below. iOS clients do not currently support routing IPv6 traffic through the IKEv2 VPN; you may instead use [OpenVPN](https://github.com/hwdsl2/openvpn-install) or [WireGuard](https://github.com/hwdsl2/wireguard-install).
 
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