pppd（点对点协议）不适用于我的自定义嵌入式linux

我在标准rasbiany（raspberry pi 3b）上使用pppd很长时间了，从来没有遇到任何连接互联网的问题。 但这一次，我正在使用raspberry的定制linux映像（由yocto生成），并面临连接internet的问题，如下面的日志所示。raspberry和4g调制解调器之间的UART连接工作正常。 请给我同样的建议。 谢谢

ATZ
好啊
AT+CGDCONT=1，“IP”，“portalnmms”，0,0
好啊
ATD*99#
连接
脚本chat-v-f/etc/ppp/chat/4g.chat已完成（pid 6198），状态=0x0
串行连接已建立。
使用第30频道
使用ppp0接口
连接：ppp0/dev/ttyam0
警告-机密文件/etc/ppp/pap secrets具有世界和/或组访问权限
已发送[LCP ConfReq id=0x1c]
rcvd[LCP ConfReq id=0x74]
已发送[LCP ConfNak id=0x74]
rcvd[LCP确认id=0x1c]
rcvd[LCP ConfReq id=0x75]
已发送[LCP确认id=0x75]
已发送[LCP EchoReq id=0x0 magic=0xa8f80db7]
警告-机密文件/etc/ppp/pap secrets具有世界和/或组访问权限
已发送[PAP AuthReq id=0xa user=“raspberrypi3”密码=]
rcvd[LCP离散id=0x76 magic=0xCFCFCFA215]
rcvd[LCP EchoRep id=0x0 magic=0xCFCFFA215 a8 f8 0d b7]
rcvd[PAP认证id=0xa”“]
PAP身份验证成功
已发送[CCP ConfReq id=0xa]
已发送[IPCP ConfReq id=0xa]
rcvd[LCP ProtRej id=0x77 80 fd 01 0a 00 0f 1a 04 78 00 18 04 78 00 15 03 2f]
接收到“压缩控制协议”（0x80fd）的协议拒绝
已发送[IPCP ConfReq id=0xa]
已发送[IPCP ConfReq id=0xa]
已发送[IPCP ConfReq id=0xa]
已发送[IPCP ConfReq id=0xa]
已发送[IPCP ConfReq id=0xa]
已发送[IPCP ConfReq id=0xa]
已发送[IPCP ConfReq id=0xa]
已发送[IPCP ConfReq id=0xa]
已发送[IPCP ConfReq id=0xa]
已发送[LCP EchoReq id=0x1 magic=0xa8f80db7]
IPCP:发送配置请求超时
已发送[LCP TermReq id=0x1d“无网络协议运行”]
已发送[LCP TermReq id=0x1e“无网络协议运行”]
连接已终止。
调制解调器挂断

ATZ
OK
AT+CGDCONT=1,"IP","portalnmms","",0,0
OK
ATD*99#
CONNECT
Script chat -v -f /etc/ppp/chat/4g.chat finished (pid 6198), status = 0x0
Serial connection established.
using channel 30
Using interface ppp0
Connect: ppp0 <--> /dev/ttyAMA0
Warning - secret file /etc/ppp/pap-secrets has world and/or group access
sent [LCP ConfReq id=0x1c <asyncmap 0xa0000> <magic 0xa8f80db7> <pcomp> <accomp>]
rcvd [LCP ConfReq id=0x74 <asyncmap 0x0> <auth chap MD5> <magic 0xcfcfa215> <pcomp> <accomp>]
sent [LCP ConfNak id=0x74 <auth pap>]
rcvd [LCP ConfAck id=0x1c <asyncmap 0xa0000> <magic 0xa8f80db7> <pcomp> <accomp>]
rcvd [LCP ConfReq id=0x75 <asyncmap 0x0> <auth pap> <magic 0xcfcfa215> <pcomp> <accomp>]
sent [LCP ConfAck id=0x75 <asyncmap 0x0> <auth pap> <magic 0xcfcfa215> <pcomp> <accomp>]
sent [LCP EchoReq id=0x0 magic=0xa8f80db7]
Warning - secret file /etc/ppp/pap-secrets has world and/or group access
sent [PAP AuthReq id=0xa user="raspberrypi3" password=<hidden>]
rcvd [LCP DiscReq id=0x76 magic=0xcfcfa215]
rcvd [LCP EchoRep id=0x0 magic=0xcfcfa215 a8 f8 0d b7]
rcvd [PAP AuthAck id=0xa ""]
PAP authentication succeeded
sent [CCP ConfReq id=0xa <deflate 15> <deflate(old#) 15> <bsd v1 15>]
sent [IPCP ConfReq id=0xa <compress VJ 0f 01> <addr 0.0.0.0> <ms-dns1 0.0.0.0> <ms-dns2 0.0.0.0>]
rcvd [LCP ProtRej id=0x77 80 fd 01 0a 00 0f 1a 04 78 00 18 04 78 00 15 03 2f]
Protocol-Reject for 'Compression Control Protocol' (0x80fd) received
sent [IPCP ConfReq id=0xa <compress VJ 0f 01> <addr 0.0.0.0> <ms-dns1 0.0.0.0> <ms-dns2 0.0.0.0>]
sent [IPCP ConfReq id=0xa <compress VJ 0f 01> <addr 0.0.0.0> <ms-dns1 0.0.0.0> <ms-dns2 0.0.0.0>]
sent [IPCP ConfReq id=0xa <compress VJ 0f 01> <addr 0.0.0.0> <ms-dns1 0.0.0.0> <ms-dns2 0.0.0.0>]
sent [IPCP ConfReq id=0xa <compress VJ 0f 01> <addr 0.0.0.0> <ms-dns1 0.0.0.0> <ms-dns2 0.0.0.0>]
sent [IPCP ConfReq id=0xa <compress VJ 0f 01> <addr 0.0.0.0> <ms-dns1 0.0.0.0> <ms-dns2 0.0.0.0>]
sent [IPCP ConfReq id=0xa <compress VJ 0f 01> <addr 0.0.0.0> <ms-dns1 0.0.0.0> <ms-dns2 0.0.0.0>]
sent [IPCP ConfReq id=0xa <compress VJ 0f 01> <addr 0.0.0.0> <ms-dns1 0.0.0.0> <ms-dns2 0.0.0.0>]
sent [IPCP ConfReq id=0xa <compress VJ 0f 01> <addr 0.0.0.0> <ms-dns1 0.0.0.0> <ms-dns2 0.0.0.0>]
sent [IPCP ConfReq id=0xa <compress VJ 0f 01> <addr 0.0.0.0> <ms-dns1 0.0.0.0> <ms-dns2 0.0.0.0>]
sent [LCP EchoReq id=0x1 magic=0xa8f80db7]
IPCP: timeout sending Config-Requests
sent [LCP TermReq id=0x1d "No network protocols running"]
sent [LCP TermReq id=0x1e "No network protocols running"]
Connection terminated.
Modem hangup