We have over hundred hardware devices that connect to T-mobile 4G LTE network. What we notice is that few devices (or SIM) ALWAYS work fine and some NEVER.
- In every case, the failure is at the same point.
1.1. Bad case - Modem hangs up after LCP stage of PPP protocol (no IPCP packets received from t-mobile)
1.2. Good case - IPCP packets are received from t-mobile after the LCP stage. Network works fine.
- All devices have the same Firmware/Software and configurations. Exactly the same.
Bad case - Notice that modem hangs up suddenly, terminating connection as IPCP packers are not received from t-mobile
2022-11-16T06:13:01.164991 pppd[13805]: pppd 2.4.7 started by root, uid 0
2022-11-16T06:13:03.384823 pppd[13805]: Script /usr/bin/gsmchat.lua fast.t-mobile.com finished (pid 13827), status = 0x0
2022-11-16T06:13:03.384922 pppd[13805]: Serial connection established.
2022-11-16T06:13:03.386535 pppd[13805]: using channel 555
2022-11-16T06:13:03.387721 pppd[13805]: Using interface ppp0
2022-11-16T06:13:03.394827 pppd[13805]: Connect: ppp0 <--> /dev/ttyUSB4
2022-11-16T06:13:04.396459 pppd[13805]: sent [LCP ConfReq id=0x1 <asyncmap 0x0> <magic 0x44106a48> <pcomp> <accomp>]
2022-11-16T06:13:04.399890 pppd[13805]: rcvd [LCP ConfReq id=0x0 <asyncmap 0x0> <auth chap MD5> <magic 0xbf2d522c> <pcomp> <accomp>]
2022-11-16T06:13:04.399972 pppd[13805]: No auth is possible
2022-11-16T06:13:04.400019 pppd[13805]: sent [LCP ConfRej id=0x0 <auth chap MD5>]
2022-11-16T06:13:04.400135 pppd[13805]: rcvd [LCP ConfAck id=0x1 <asyncmap 0x0> <magic 0x44106a48> <pcomp> <accomp>]
2022-11-16T06:13:04.401739 pppd[13805]: rcvd [LCP ConfReq id=0x1 <asyncmap 0x0> <magic 0xbf2d522c> <pcomp> <accomp>]
2022-11-16T06:13:04.401822 pppd[13805]: sent [LCP ConfAck id=0x1 <asyncmap 0x0> <magic 0xbf2d522c> <pcomp> <accomp>]
2022-11-16T06:13:04.402269 pppd[13805]: sent [CCP ConfReq id=0x1 <deflate 15> <deflate(old#) 15> <bsd v1 15>]
2022-11-16T06:13:04.402406 pppd[13805]: sent [IPCP ConfReq id=0x1 <addr 0.0.0.0> <ms-dns1 0.0.0.0> <ms-dns2 0.0.0.0>]
2022-11-16T06:13:04.403773 pppd[13805]: rcvd [LCP DiscReq id=0x2 magic=0xbf2d522c]
2022-11-16T06:13:04.403884 pppd[13805]: rcvd [LCP ProtRej id=0x3 80 fd 01 01 00 0f 1a 04 78 00 18 04 78 00 15 03 2f]
2022-11-16T06:13:04.403930 pppd[13805]: Protocol-Reject for 'Compression Control Protocol' (0x80fd) received
2022-11-16T06:13:04.436989 pppd[13805]: Modem hangup
2022-11-16T06:13:04.437090 pppd[13805]: Connection terminated.
2022-11-16T06:13:05.479995 pppd[13805]: Exit.
Good case - IPCP packets are received from t-mobile after the LCP stage. Network works fine.
2022-11-16T06:13:01.164991 pppd[13805]: pppd 2.4.7 started by root, uid 0
2022-11-16T06:13:03.384823 pppd[13805]: Script /usr/bin/gsmchat.lua fast.t-mobile.com finished (pid 13827), status = 0x0
2022-11-16T06:13:03.384922 pppd[13805]: Serial connection established.
2022-11-17T10:55:39.325029 pppd[29699]: pppd 2.4.7 started by root, uid 0
2022-11-17T10:55:45.490444 pppd[29699]: Script /usr/bin/gsmchat.lua fast.t-mobile.com finished (pid 29700), status = 0x0
2022-11-17T10:55:45.490538 pppd[29699]: Serial connection established.
2022-11-17T10:55:45.492159 pppd[29699]: using channel 4
2022-11-17T10:55:45.493311 pppd[29699]: Using interface ppp0
2022-11-17T10:55:45.493916 pppd[29699]: Connect: ppp0 <--> /dev/ttyUSB4
2022-11-17T10:55:46.495477 pppd[29699]: sent [LCP ConfReq id=0x1 <asyncmap 0x0> <magic 0x3be804a0> <pcomp> <accomp>]
2022-11-17T10:55:46.501899 pppd[29699]: rcvd [LCP ConfReq id=0x0 <asyncmap 0x0> <auth chap MD5> <magic 0xc5564603> <pcomp> <accomp>]
2022-11-17T10:55:46.502015 pppd[29699]: No auth is possible
2022-11-17T10:55:46.502071 pppd[29699]: sent [LCP ConfRej id=0x0 <auth chap MD5>]
2022-11-17T10:55:46.502190 pppd[29699]: rcvd [LCP ConfAck id=0x1 <asyncmap 0x0> <magic 0x3be804a0> <pcomp> <accomp>]
2022-11-17T10:55:46.503887 pppd[29699]: rcvd [LCP ConfReq id=0x1 <asyncmap 0x0> <magic 0xc5564603> <pcomp> <accomp>]
2022-11-17T10:55:46.504001 pppd[29699]: sent [LCP ConfAck id=0x1 <asyncmap 0x0> <magic 0xc5564603> <pcomp> <accomp>]
2022-11-17T10:55:46.504423 pppd[29699]: sent [CCP ConfReq id=0x1 <deflate 15> <deflate(old#) 15> <bsd v1 15>]
2022-11-17T10:55:46.504544 pppd[29699]: sent [IPCP ConfReq id=0x1 <addr 0.0.0.0> <ms-dns1 0.0.0.0> <ms-dns2 0.0.0.0>]
2022-11-17T10:55:46.505922 pppd[29699]: rcvd [LCP DiscReq id=0x2 magic=0xc5564603]
2022-11-17T10:55:46.507740 pppd[29699]: rcvd [LCP ProtRej id=0x3 80 fd 01 01 00 0f 1a 04 78 00 18 04 78 00 15 03 2f]
2022-11-17T10:55:46.507807 pppd[29699]: Protocol-Reject for 'Compression Control Protocol' (0x80fd) received
2022-11-17T10:55:46.533535 pppd[29699]: rcvd [IPCP ConfReq id=0x0]
2022-11-17T10:55:46.533631 pppd[29699]: sent [IPCP ConfNak id=0x0 <addr 0.0.0.0>]
2022-11-17T10:55:46.533802 pppd[29699]: rcvd [IPCP ConfNak id=0x1 <addr 100.161.62.192> <ms-dns1 10.177.0.34> <ms-dns2 10.177.0.210>]
2022-11-17T10:55:46.533895 pppd[29699]: sent [IPCP ConfReq id=0x2 <addr 100.161.62.192> <ms-dns1 10.177.0.34> <ms-dns2 10.177.0.210>]
2022-11-17T10:55:46.535641 pppd[29699]: rcvd [IPCP ConfReq id=0x1]
2022-11-17T10:55:46.535921 pppd[29699]: sent [IPCP ConfAck id=0x1]
2022-11-17T10:55:46.536107 pppd[29699]: rcvd [IPCP ConfAck id=0x2 <addr 100.161.62.192> <ms-dns1 10.177.0.34> <ms-dns2 10.177.0.210>]
2022-11-17T10:55:46.536161 pppd[29699]: Could not determine remote IP address: defaulting to 10.64.64.64
2022-11-17T10:55:46.541811 pppd[29699]: local IP address 100.161.62.192
2022-11-17T10:55:46.542468 pppd[29699]: remote IP address 10.64.64.64
2022-11-17T10:55:46.542939 pppd[29699]: primary DNS address 10.177.0.34
2022-11-17T10:55:46.543274 pppd[29699]: secondary DNS address 10.177.0.210
2022-11-17T10:55:46.545424 pppd[29699]: Script /etc/ppp/ip-up started (pid 29706)
2022-11-17T10:55:46.932589 pppd[29699]: Script /etc/ppp/ip-up finished (pid 29706), status = 0x0
2022-11-17T11:02:31.746597 pppd[29699]: Terminating on signal 15
2022-11-17T11:02:31.747046 pppd[29699]: Connect time 6.8 minutes.
2022-11-17T11:02:31.747199 pppd[29699]: Sent 38655 bytes, received 45408 bytes.
The network connections were working fine till September but few devices have stopped working randomly from October onwards (different dates)
Any help would be appreciated.
