https://wiki.openwrt.org/doc/howto/vpn.server.pptpd
Clients configuration is located in /etc/config/pptpd. Modify it to enable pptpd and configure clients and network. Following is example for two clients. You can add multiple config 'login'.
config service 'pptpd'
option 'enabled' '1'
option 'localip' ‘xxx.yyy.www.zzz’config 'login'
option 'username' ‘foo’
option 'password' ‘bar’
option 'remoteip' 'xxx.yyy.zzz.1’config 'login'
option 'username' ‘foo’
option 'password' ‘bar’
option 'remoteip' 'xxx.yyy.zzz.2’
Ok...
root@OpenWrt:~# cat /etc/config/pptpd
config service 'pptpd'
option 'enabled' '1'
option 'localip' '192.168.11.10'
option 'remoteip' '192.168.11.11-25'config 'login'
option 'username' 'user'
option 'password' 'Qwe12345'
option 'remoteip' '192.168.11.16'
reboot... ps
/usr/sbin/pppd local file /etc/ppp/options.pptpd 115200 192.168.11.10:192.168.11.11 ipparam 217.xxx.99.90 remotenumber 217.xxx.99.90