Modem resetting randomly

[Tgdc1978]

Hi. I have an EM7565 on a ZBT WG3526. I am on AT&T with an external antenna. I typically get quite good speeds. Sometimes even 100Mbps down and 15Mbps up with 3x CA. For several weeks it worked fine but more recently we see the signal dropping periodically and comping back a minute or two later. Looking at the debug log from GoldenOrb I see that the modem appears to reset becoming unreachable and then starting back up:

******
AT!PCTEMP?
Temp state: Normal
Temperature: 37.00 C
OK

Sun Sep 5 09:36:47 2021 : /dev/ttyUSB2

Sun Sep 5 09:36:48 2021 : /dev/ttyUSB2 Can't open device /dev/ttyUSB2.

Sun Sep 5 09:37:23 2021 : /dev/ttyUSB2 AT!ENTERCND="A710";!BAND?
Index, Name, GW Band Mask L Band Mask 1 TDS Band Mask L Band Mask 2 L Band Mask 3 L Band Mask 4
00, All bands 100600000EC00000 00002100BA0E19DF 0000000000000000 0000000000000002 0000000000000000 0000000000000000
OK

Sun Sep 5 09:37:24 2021 : /dev/ttyUSB2 AT!SELRAT?
!SELRAT: 06, LTE Only
OK

****

It doesn’t appear to be overheating and I have upgraded to the larger 3A power supply. I tried reflashing to the latest generic firmware and reseating the card but have the same behavior. The signal strength seems decent:

****
GSTATUS:
Current Time: 393 Temperature: 38
Reset Counter: 53 Mode: ONLINE
System mode: LTE PS state: Attached
LTE band: B2 LTE bw: 20 MHz
LTE Rx chan: 850 LTE Tx chan: 18850
LTE SCC1 state:NOT ASSIGNED
LTE SCC2 state:NOT ASSIGNED
LTE SCC3 state:NOT ASSIGNED
LTE SCC4 state:NOT ASSIGNED
EMM state: Registered Normal Service
RRC state: RRC Connected
IMS reg state: No Srv
PCC RxM RSSI: -63 PCC RxM RSRP: -95
PCC RxD RSSI: -64 PCC RxD RSRP: -96
Tx Power: -- TAC: 1238 (4664)
RSRQ (dB): -12.7 Cell ID: 0114e20a (18145802)
SINR (dB): 12.4
OK
AT!PCTEMP?
Temp state: Normal
Temperature: 39.00 C
OK

Sun Sep 5 09:43:32 2021 : /dev/ttyUSB2 AT+CPMS="SM"
+CPMS: 29,30,29,30,29,30
OK
****

Any ideas on what to try? It is not always on B2. It also often uses B66 and sometimes B12.

Thanks.

[Rich Hathaway]

While I am not familiar with that module, It will tell you what is going on, dmesg it and get a thorough log,

[Tgdc1978]

Thanks. How do I do that? Is DMESG an AT command?

[Tgdc1978]

Ah, Google helped with dmesg. This appears to be the set of entries from when a reset is happening:

[ 756.068362] WARNING: CPU: 1 PID: 0 at net/sched/sch_generic.c:320 dev_watchdog+0x1ac/0x324
[ 756.076615] NETDEV WATCHDOG: wwan0 (qmi_wwan): transmit queue 0 timed out
[ 756.083371] Modules linked in: ksmbd rt2800usb rt2800lib qcserial pppoe ppp_async option cdc_mbim usb_wwan sierra_net sierra rt2x00usb rt2x00lib rndis_host qmi_wwan pppox ppp_generic nft_set_rbtree nft_set_hash nft_reject_ipv6 nft_reject_ipv4 nft_reject_inet nft_reject_bridge nft_reject nft_redir nft_quota nft_numgen nft_meta_bridge nft_meta nft_log nft_limit nft_fwd_netdev nft_exthdr nft_dup_netdev nft_ct nft_counter nft_chain_route_ipv6 nft_chain_route_ipv4 nf_tables_netdev nf_tables_ipv6 nf_tables_ipv4 nf_tables_inet nf_tables_bridge nf_tables nf_conntrack_ipv6 mt76x2e mt76x2_common mt76x02_lib mt7603e mt76 mac80211 iptable_nat ipt_REJECT ipt_MASQUERADE huawei_cdc_ncm cfg80211 cdc_ncm cdc_ether xt_time xt_tcpudp xt_tcpmss xt_statistic xt_state xt_recent xt_nat xt_multiport xt_mark xt_mac xt_limit
[ 756.109709] usb 1-2: USB disconnect, device number 2
[ 756.154113] xt_length xt_hl xt_helper xt_ecn xt_dscp xt_conntrack xt_connmark xt_connlimit xt_connbytes xt_comment xt_TCPMSS xt_REDIRECT xt_LOG xt_HL xt_FLOWOFFLOAD xt_DSCP xt_CT xt_CLASSIFY wireguard usbserial usbnet usblp slhc nfnetlink nf_reject_ipv4 nf_nat_redirect nf_nat_masquerade_ipv4 nf_conntrack_ipv4 nf_nat_ipv4 nf_nat nf_log_ipv4 nf_flow_table_hw nf_flow_table nf_dup_netdev nf_defrag_ipv6 nf_defrag_ipv4 nf_conntrack_rtcache iptable_raw iptable_mangle iptable_filter ipt_ECN ipheth ip_tables crc_ccitt compat cdc_wdm cdc_acm fuse sch_cake nf_conntrack sch_tbf sch_ingress sch_htb sch_hfsc em_u32 cls_u32 cls_tcindex cls_route cls_matchall cls_fw cls_flow cls_basic act_skbedit act_mirred ledtrig_usbport nf_log_ipv6 nf_log_common ip6table_mangle ip6table_filter ip6_tables ip6t_REJECT x_tables
[ 756.159850] qcserial ttyUSB0: Qualcomm USB modem converter now disconnected from ttyUSB0
[ 756.229693] nf_reject_ipv6 ifb ip6_udp_tunnel udp_tunnel tun vfat fat hfs nls_utf8 nls_iso8859_1 nls_cp437 sha512_generic sha256_generic seqiv jitterentropy_rng drbg md5 md4 hmac ghash_generic gf128mul gcm ecb des_generic ctr cmac ccm mmc_block usb_storage mtk_sd mmc_core leds_gpio xhci_plat_hcd xhci_pci xhci_mtk xhci_hcd uhci_hcd ohci_platform ohci_hcd ahci libahci libata ehci_platform sd_mod scsi_mod ehci_hcd gpio_button_hotplug ext4 mbcache jbd2 exfat usbcore nls_base usb_common mii crc32c_generic
[ 756.238340] qcserial 1-2:1.0: device disconnected
[ 756.282357] CPU: 1 PID: 0 Comm: swapper/1 Not tainted 4.14.215 #0
[ 756.282369] Stack : 00000000 806f0000 00000000 00000000 805b0000 80555214 00000000 00000000
[ 756.288378] qcserial ttyUSB1: Qualcomm USB modem converter now disconnected from ttyUSB1
[ 756.293162] 80520afc 8fc0bdc4
[ 756.301938] qcserial 1-2:1.2: device disconnected
[ 756.309544] 8fc3c33c 8058e907 8051b890 00000001 8fc0bd68 ac07f5ce
[ 756.309571] 00000000 00000000 806f0000 03d96c6f 00000001 806ffa58 77c8c7d3 002242f1
[ 756.309603] 00000000
[ 756.315378] qcserial ttyUSB2: Qualcomm USB modem converter now disconnected from ttyUSB2
[ 756.317953] 80590000
[ 756.324440] qcserial 1-2:1.3: device disconnected
[ 756.332417] 0000015d
[ 756.337535] qmi_wwan 1-2:1.8 wwan0: unregister 'qmi_wwan' usb-1e1c0000.xhci-2, WWAN/QMI device
[ 756.343336] 80720000 00000000 805b0000 00000000 8054f2a4
[ 756.366485] 80377200 00000140 00000001 8fd4f040 00000001 80590000 00000004 806f0004
[ 756.374838] ...
[ 756.377281] Call Trace:
[ 756.379754] [<8000c7b0>] show_stack+0x58/0x100
[ 756.384208] [<8045c4e4>] dump_stack+0xa4/0xe0
[ 756.388563] [<8002f798>] __warn+0xe0/0x138
[ 756.392647] [<8002f820>] warn_slowpath_fmt+0x30/0x3c
[ 756.397627] [<80377200>] dev_watchdog+0x1ac/0x324
[ 756.402347] [<80089758>] call_timer_fn.isra.25+0x24/0x84
[ 756.407647] [<80089a14>] run_timer_softirq+0x1bc/0x248
[ 756.412791] [<8047a3b0>] __do_softirq+0x128/0x2ec
[ 756.417493] [<80034164>] irq_exit+0xac/0xc8
[ 756.421667] [<80250f80>] plat_irq_dispatch+0xfc/0x138
[ 756.426708] [<80007588>] except_vec_vi_end+0xb8/0xc4
[ 756.431658] [<80008f50>] r4k_wait_irqoff+0x1c/0x24
[ 756.436546] ---[ end trace 92bd2fc1730020b9 ]---
[ 757.333799] usb 1-2: new high-speed USB device number 3 using xhci-mtk
[ 757.525466] qcserial 1-2:1.0: Qualcomm USB modem converter detected
[ 757.532532] usb 1-2: Qualcomm USB modem converter now attached to ttyUSB0
[ 757.541657] usb 1-2: USB disconnect, device number 3
[ 757.547742] qcserial ttyUSB0: Qualcomm USB modem converter now disconnected from ttyUSB0
[ 757.556486] qcserial 1-2:1.0: device disconnected
[ 766.373258] usb 1-2: new high-speed USB device number 4 using xhci-mtk
[ 766.553827] usb 1-2: config 1 has an invalid interface number: 8 but max is 3
[ 766.560960] usb 1-2: config 1 has no interface number 1
[ 766.571185] qcserial 1-2:1.0: Qualcomm USB modem converter detected
[ 766.578272] usb 1-2: Qualcomm USB modem converter now attached to ttyUSB0
[ 766.587360] qcserial 1-2:1.2: Qualcomm USB modem converter detected
[ 766.594416] usb 1-2: Qualcomm USB modem converter now attached to ttyUSB1
[ 766.603562] qcserial 1-2:1.3: Qualcomm USB modem converter detected
[ 766.610647] usb 1-2: Qualcomm USB modem converter now attached to ttyUSB2
[ 766.620174] qmi_wwan 1-2:1.8: cdc-wdm0: USB WDM device
[ 766.627381] qmi_wwan 1-2:1.8 wwan0: register 'qmi_wwan' at usb-1e1c0000.xhci-2, WWAN/QMI device, 86:0b:76:24:61:b8

[Rich Hathaway]

post the whole log,
in the first line you can see the kernel panic cpu which then causes the obvious timeout which then leads to the disconnections, what happens before the line 1

[Didneywhorl]

Ah, Google helped with dmesg. This appears to be the set of entries from when a reset is happening:
...

Did you see Richs' comment?

[kz333]

Make sure your power supply is capable and the power is stable. If you aren't supplying additional input power, you should always do so if the capability exists.