how to install a vpn server in OpenWrt Barrier Breaker 14.07, i tried to configure pptp (https://openwrt.org/docs/guide-user/services/vpn/pptp/basic) but badly i can not connect to it please help me
Your first step should be to upgrade to a current release as there are no current, secure packages for Barrier Breaker available. Barrier Breaker is no longer supported and should be considered insecure.
Most of the documentation has been updated over the four years since Barrier Breaker was released. There have been significant changes in how OpenWrt operates and is configured since then.
Is there a reason you need PPTP? Microsoft's "style" of PPTP is considered very insecure and there are many better alternatives available today, even for low-power devices.
From the page you linked
As it is today PPTP with MS-CHAP-v2 encryption is not secure and should not be used
See also, for example
Firstly I thank you for your help, I used this PPTP protocol to simplify the simple things and tested the connection to the server pptpd, I inform you that I am a beginner in this area and I am looking for this connection to my router remote, is there another method ??? like openvpn which is compatible with OpenWrt Barrier Breaker 14.07.
Many people here use OpenVPN or Wireguard with current releases of OpenWrt. Both have clients for a wide range of devices, desktops, laptops, iOS and Android devices that are typically "free" to use.
Which router do you have and perhaps we can help you upgrade to a version that has current packages and matches the instruction you've been reading?