PandoraBox连接vpn时出现错误Non-zero Async Control Character Maps are not supported! 其大概意思是不支持非零Async控制字符映射！

Wed May 10 21:19:44 2017 daemon.info pppd[3806]: Using interface pptp-vpn135
Wed May 10 21:19:44 2017 daemon.notice pppd[3806]: Connect: pptp-vpn135 <--> pptp (202.198.96.135)
Wed May 10 21:19:44 2017 daemon.warn pppd[3891]: Non-zero Async Control Character Maps are not supported!
Wed May 10 21:19:44 2017 daemon.warn pppd[3891]: Non-zero Async Control Character Maps are not supported!
Wed May 10 21:19:44 2017 daemon.info pppd[3806]: LCP terminated by peer (Q^Y#M-a^@<M-Mt^@^@^CM-.)
Wed May 10 21:19:47 2017 daemon.notice pppd[3806]: Connection terminated.
Wed May 10 21:19:47 2017 daemon.notice pppd[3806]: Modem hangup

编辑路由器中pppd中的options的文件，添加内容为

refuse-eap
refuse-pap

并且注释掉lock：

[root@PandoraBox_FF6F1A:/root]#cat /etc/ppp/options
#debug
logfile /dev/null
noipdefault
noaccomp
nopcomp
nocrtscts
refuse-eap
refuse-pap
#lock
maxfail 0
#PPP超时参数设置
lcp-echo-failure 15  #发送间隔秒
lcp-echo-interval 3  #重复次数

主要的原因是MS-CHAP v2验证方式