首先，很抱歉提出这个问题，如果很明显的话，我不太擅长网络配置。
我目前正在尝试通过调制解调器将装有 Busybox 的 Linux 机器连接到蜂窝网络 (T-Mobile NL)。ppp根据网络参数，ppp成功连接到调制解调器，但在启动 IPCP 协商时，调制解调器挂断，没有任何错误指示。我唯一能想到的是它与 IPCP 协商有关，因为这是调制解调器挂断的连接步骤。
这是我的配置：
ppp 选项：
/dev/modem_at0
lock
debug
logfile /var/log/ppplog
115200
linkname ppp0
defaultroute
replacedefaultroute
auth
user "tmobile"
password "tmobile"
crtscts
holdoff 3
persist
connect '/usr/sbin/chat -v -t 90 -f /etc/ppp/peers/gsm_chat'
disconnect "chat -- \d+++\d\c OK ath0 OK"
noipdefault
novj
novjccomp
noaccomp
nobsdcomp
novj
noccp
ipcp-accept-local
ipcp-accept-remote
ipcp-restart 15
ipcp-max-failure 10
ipcp-restart 10
maxfail 40
ipv6cp-restart 15
调制解调器聊天：（/etc/ppp/peers/gsm_chat）
SAY "GSM chat\n"
ECHO OFF
ABORT 'NO DIAL TONE'
ABORT 'NO DIALTONE'
ABORT 'NO ANSWER'
ABORT 'NO CARRIER'
ABORT 'DELAYED'
ABORT 'VOICE'
ABORT 'BUSY'
'' 'AT'
OK 'ATZ'
OK 'AT+CSQ'
OK 'AT+CPIN=****'
# Added the correct pin just above
REPORT CONNECT
OK 'AT+CGDCONT=1,"IP","smartsites.t-mobile"'
SAY "Dialing...\n"
OK 'ATD*99#'
SAY "Waiting for CONNECT...\n"
TIMEOUT 120
CONNECT ''
SAY "Connected\n"
日志：
GSM chat
Dialing...
Waiting for CONNECT...
Connected
chat: May 08 06:28:47 CONNECT 100000000
Script /usr/sbin/chat -v -t 90 -f /etc/ppp/peers/gsm_chat finished (pid 604), status = 0x0
Serial connection established.
using channel 1
Using interface ppp0
Connect: ppp0 <--> /dev/modem_at0
sent [LCP ConfReq id=0x1 <asyncmap 0x0> <auth eap> <magic 0x1dabaabe> <pcomp>]
rcvd [LCP ConfReq id=0x0 <asyncmap 0x0> <auth chap MD5> <magic 0x451d49cd> <pcomp> <accomp>]
sent [LCP ConfRej id=0x0 <accomp>]
rcvd [LCP ConfRej id=0x1 <auth eap>]
sent [LCP ConfReq id=0x2 <asyncmap 0x0> <auth chap MD5> <magic 0x1dabaabe> <pcomp>]
rcvd [LCP ConfReq id=0x1 <asyncmap 0x0> <auth chap MD5> <magic 0x451d49cd> <pcomp>]
sent [LCP ConfAck id=0x1 <asyncmap 0x0> <auth chap MD5> <magic 0x451d49cd> <pcomp>]
rcvd [LCP ConfRej id=0x2 <auth chap MD5>]
sent [LCP ConfReq id=0x3 <asyncmap 0x0> <magic 0x1dabaabe> <pcomp>]
rcvd [LCP ConfAck id=0x3 <asyncmap 0x0> <magic 0x1dabaabe> <pcomp>]
Warning - secret file /etc/ppp/pap-secrets has world and/or group access
rcvd [LCP DiscReq id=0x2 magic=0x451d49cd]
rcvd [CHAP Challenge id=0x1 <06caf8ebf2c8971a809509e3f27a368a>, name = "UMTS_CHAP_SRVR"]
sent [CHAP Response id=0x1 <ceb886dabe81e0d6484f903ae4ad2d5d>, name = "tmobile"]
rcvd [CHAP Success id=0x1 ""]
CHAP authentication succeeded
CHAP authentication succeeded
sent [IPCP ConfReq id=0x1 <addr 0.0.0.0>]
Hangup (SIGHUP)
Modem hangup
Connection terminated.
为了确定问题是否来自网络提供商，我尝试使用另一张 SIM 卡（来自 Vodafone NL），即使重新配置后，连接仍然挂起。因此，我猜想问题要么来自机器，要么来自我的配置。
有人知道问题可能出在哪里吗，或者我如何更详细地调查这个问题？
如果您认为任何细节有助于更清楚地了解该问题，请告诉我！