[lwip-users] Question about pppos sometimes fail to reach internet

[Axel Lin]

Hi,
I got below log after ppp_connect() success:

[00:14:27:457] AT+CEREG?␍␍␊
[00:14:27:461] +CEREG: 0,1␍␊
[00:14:27:461] ␍␊
[00:14:27:461] OK␍␊
[00:14:27:688] AT+CGDCONT=1,"IP","internet"␍␍␊
[00:14:27:692] OK␍␊
[00:14:28:504] AT+CGAUTH=1,1,"us","address@hidden"␍␍␊
[00:14:28:508] OK␍␊
[00:14:28:969] ATD*99***1#␍␍␊
[00:14:28:972] CONNECT␍␊
[00:14:28:972] netif: setting default interface pp␍␊
[00:14:28:981] ppp_connect[0]: holdoff=0␍␊
[00:14:28:981] ppp phase changed[0]: phase=3␍␊
[00:14:28:981] pppos_connect: unit 0: connecting␍␊
[00:14:28:985] ppp_start[0]␍␊
[00:14:28:985] ppp phase changed[0]: phase=6␍␊
[00:14:28:988] pppos_send_config[0]: out_accm=FF FF FF FF␍␊
[00:14:28:992] ppp_send_config[0]␍␊
[00:14:28:997] pppos_recv_config[0]: in_accm=FF FF FF FF␍␊
[00:14:29:001] ppp_recv_config[0]␍␊
[00:14:29:001] ppp: auth protocols: PAP=0 CHAP=0 CHAP_MD5=0␍␊
[00:14:29:012] pppos_write[0]: len=24␍␊
[00:14:29:020] ppp_start[0]: finished␍␊
[00:14:29:180] pppos_input[0]: got 68 bytes␍␊
[00:14:29:198] pppos_write[0]: len=24␍␊
[00:14:29:214] pppos_input[0]: got 22 bytes␍␊
[00:14:29:228] netif_set_mtu[0]: mtu=1500␍␊
[00:14:29:228] pppos_send_config[0]: out_accm=0 0 0 0␍␊
[00:14:29:228] ppp_send_config[0]␍␊
[00:14:29:228] pppos_recv_config[0]: in_accm=0 0 0 0␍␊
[00:14:29:240] ppp_recv_config[0]␍␊
[00:14:29:240] ppp phase changed[0]: phase=7␍␊
[00:14:29:240] ppp phase changed[0]: phase=9␍␊
[00:14:29:253] pppos_write[0]: len=32␍␊
[00:14:29:262] pppos_input[0]: got 13 bytes␍␊
[00:14:29:273] pppos_write[0]: len=12␍␊
[00:14:29:281] pppos_input[0]: got 21 bytes␍␊
[00:14:29:292] pppos_write[0]: len=20␍␊
[00:14:29:302] pppos_input[0]: got 27 bytes␍␊
[00:14:29:311] pppos_write[0]: len=32␍␊
[00:14:29:337] pppos_input[0]: got 33 bytes␍␊
[00:14:29:350] sifvjcomp[0]: VJ compress enable=1 slot=1 max slot=15␍␊
[00:14:29:350] sifup[0]: err_code=0␍␊
[00:14:29:350] status_cb: err_code=0␍␍␊
[00:14:29:361] status_cb: Connected␍␊
[00:14:29:361]    our_ipaddr  = 10.0.2.66␍␊
[00:14:29:361]    his_ipaddr  = 10.0.2.55␍␊
[00:14:29:361]    netmask     = 255.255.255.255␍␊
[00:14:29:361]    dns1        = 10.0.2.55␍␊
[00:14:29:375]    dns2        = 10.0.2.55␍␊
[00:14:29:375] local  IP address 10.0.2.66␍␊
[00:14:29:375] remote IP address 10.0.2.55␍␊
[00:14:29:375] primary   DNS address 10.0.2.55␍␊
[00:14:29:375] secondary DNS address 10.0.2.55␍␊
[00:14:29:388] ppp phase changed[0]: phase=10␍␊
[00:14:29:398] Network ready IP: 10.0.2.66␍␊
[00:14:29:426] // connect fails
[00:14:29:449] pppos_netif_output[0]: proto=0x21, len = 65␍␊
[00:14:35:552] // connect fails, retry
[00:14:35:592] pppos_netif_output[0]: proto=0x21, len = 65␍␊
[00:14:41:673] // connect fails, retry
[00:14:41:717] pppos_netif_output[0]: proto=0x21, len = 65␍␊
....

Sometimes the device ping 8.8.8.8 always fails.i.e. it can not reach internet.
But it's fine to ping 10.0.2.66 or 10.0.2.55.
Above log seems does not show any error.
Which part could be wrong or which part should I check about such issue?

Thanks,
Axel