<html xmlns:v="urn:schemas-microsoft-com:vml" xmlns:o="urn:schemas-microsoft-com:office:office" xmlns:w="urn:schemas-microsoft-com:office:word" xmlns:m="http://schemas.microsoft.com/office/2004/12/omml" xmlns="http://www.w3.org/TR/REC-html40"> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8"> <meta name="Generator" content="Microsoft Word 15 (filtered medium)"> <style></style> </head> <body lang="en-DK" link="#0563C1" vlink="#954F72" style="word-wrap:break-word"> <div class="WordSection1"> Hi all, <o:p></o:p> <o:p> </o:p> I am currently trying to use two SIMCOM SIM8300G-M2 5G modems to test cellular performance (coverage, latency, throughput) from two different operators in a rural area. I have been experiencing some stability issues with the modem connections. It seems that it is related to the low signal level observed in the area where I am measuring. Whenever the signal level is low, or there is no coverage, the network interface is deleted, the modem disappears from mmcli list, and it reattaches automatically after a bit, when the signal level improves. This causes long (or at least longer than I would wish) interruptions in my tests. I include some logs below as an example of what I see whenever this occurs.<o:p></o:p> <o:p> </o:p> I have tried in different hosting devices (Lenovo laptop, NUC Pro 12) and a newer version of the modems (SIMCOM SIM8380G-M2), and the problem persists. The behavior is quite erratic, I do not always see the error described above happening, but it is also appearing often enough so that it affects my measurements.<o:p></o:p> <div> <o:p> </o:p> Output from ip monitor:<o:p></o:p> </div> Deleted 4: wwan1 inet 100.77.182.96/26 brd 100.77.182.127 scope global noprefixroute wwan1<o:p></o:p> valid_lft forever preferred_lft forever<o:p></o:p> Deleted broadcast 100.77.182.127 dev wwan1 table local proto kernel scope link src 100.77.182.96 <o:p></o:p> Deleted local 100.77.182.96 dev wwan1 table local proto kernel scope host src 100.77.182.96 <o:p></o:p> Deleted 0.0.0.0 dev wwan1 lladdr 08 NOARP<o:p></o:p> 4: wwan1: <POINTOPOINT,MULTICAST,NOARP> mtu 1500 qdisc fq_codel state DOWN group default <o:p></o:p> link/none <o:p></o:p> Deleted 0.0.0.0 dev wwan1 lladdr 08 NOARP<o:p></o:p> Deleted inet wwan1 <o:p></o:p> Deleted inet6 wwan1 <o:p></o:p> Deleted 4: wwan1: <POINTOPOINT,MULTICAST,NOARP> mtu 1500 qdisc noop state DOWN group default <o:p></o:p> link/none <o:p></o:p> inet wwan1 forwarding on rp_filter loose mc_forwarding off proxy_neigh off ignore_routes_with_linkdown off <o:p></o:p> inet6 wwan1 forwarding off mc_forwarding off proxy_neigh off ignore_routes_with_linkdown off <o:p></o:p> 8: wwan1: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN group default <o:p></o:p> link/ether b2:8e:24:1d:25:20 brd ff:ff:ff:ff:ff:ff<o:p></o:p> Deleted inet wwan1 <o:p></o:p> Deleted inet6 wwan1 <o:p></o:p> Deleted 8: wwan1: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN group default <o:p></o:p> link/ether b2:8e:24:1d:25:20 brd ff:ff:ff:ff:ff:ff<o:p></o:p> inet wwan1 forwarding on rp_filter loose mc_forwarding off proxy_neigh off ignore_routes_with_linkdown off <o:p></o:p> inet6 wwan1 forwarding off mc_forwarding off proxy_neigh off ignore_routes_with_linkdown off <o:p></o:p> <o:p> </o:p> Output from dmesg, where it seems that the modem is physically disconnected?:<o:p></o:p> [Mon Aug 14 10:21:34 2023] qmi_wwan 1-3.2:1.5 wwan1: register 'qmi_wwan' at usb-0000:00:14.0-3.2, WWAN/QMI device, b2:8e:24:1d:25:20<o:p></o:p> [Mon Aug 14 10:21:36 2023] usb 1-3.2: USB disconnect, device number 7<o:p></o:p> [Mon Aug 14 10:21:36 2023] option1 ttyUSB6: GSM modem (1-port) converter now disconnected from ttyUSB6<o:p></o:p> [Mon Aug 14 10:21:36 2023] option 1-3.2:1.0: device disconnected<o:p></o:p> [Mon Aug 14 10:21:36 2023] option1 ttyUSB7: GSM modem (1-port) converter now disconnected from ttyUSB7<o:p></o:p> [Mon Aug 14 10:21:36 2023] option 1-3.2:1.1: device disconnected<o:p></o:p> [Mon Aug 14 10:21:36 2023] option1 ttyUSB8: GSM modem (1-port) converter now disconnected from ttyUSB8<o:p></o:p> [Mon Aug 14 10:21:36 2023] option 1-3.2:1.2: device disconnected<o:p></o:p> [Mon Aug 14 10:21:36 2023] option1 ttyUSB9: GSM modem (1-port) converter now disconnected from ttyUSB9<o:p></o:p> [Mon Aug 14 10:21:36 2023] option 1-3.2:1.3: device disconnected<o:p></o:p> [Mon Aug 14 10:21:36 2023] option1 ttyUSB10: GSM modem (1-port) converter now disconnected from ttyUSB10<o:p></o:p> [Mon Aug 14 10:21:36 2023] option 1-3.2:1.4: device disconnected<o:p></o:p> [Mon Aug 14 10:21:36 2023] qmi_wwan 1-3.2:1.5 wwan1: unregister 'qmi_wwan' usb-0000:00:14.0-3.2, WWAN/QMI device<o:p></o:p> [Mon Aug 14 10:21:45 2023] qmi_wwan 1-3.1:1.5: nonzero urb status received: -EPIPE<o:p></o:p> [Mon Aug 14 10:21:58 2023] usb 1-3.2: new high-speed USB device number 8 using xhci_hcd<o:p></o:p> [Mon Aug 14 10:21:58 2023] usb 1-3.2: New USB device found, idVendor=1e0e, idProduct=9001, bcdDevice= 5.04<o:p></o:p> [Mon Aug 14 10:21:58 2023] usb 1-3.2: New USB device strings: Mfr=1, Product=2, SerialNumber=3<o:p></o:p> [Mon Aug 14 10:21:58 2023] usb 1-3.2: Product: SDXLEMUR-SD-MTP _SN:AE2F01F4<o:p></o:p> [Mon Aug 14 10:21:58 2023] usb 1-3.2: Manufacturer: SIMCOM<o:p></o:p> [Mon Aug 14 10:21:58 2023] option 1-3.2:1.0: GSM modem (1-port) converter detected<o:p></o:p> [Mon Aug 14 10:21:58 2023] usb 1-3.2: GSM modem (1-port) converter now attached to ttyUSB6<o:p></o:p> [Mon Aug 14 10:21:58 2023] option 1-3.2:1.1: GSM modem (1-port) converter detected<o:p></o:p> [Mon Aug 14 10:21:58 2023] usb 1-3.2: GSM modem (1-port) converter now attached to ttyUSB7<o:p></o:p> [Mon Aug 14 10:21:58 2023] option 1-3.2:1.2: GSM modem (1-port) converter detected<o:p></o:p> [Mon Aug 14 10:21:58 2023] usb 1-3.2: GSM modem (1-port) converter now attached to ttyUSB8<o:p></o:p> [Mon Aug 14 10:21:58 2023] option 1-3.2:1.3: GSM modem (1-port) converter detected<o:p></o:p> [Mon Aug 14 10:21:58 2023] usb 1-3.2: GSM modem (1-port) converter now attached to ttyUSB9<o:p></o:p> [Mon Aug 14 10:21:58 2023] option 1-3.2:1.4: GSM modem (1-port) converter detected<o:p></o:p> [Mon Aug 14 10:21:58 2023] usb 1-3.2: GSM modem (1-port) converter now attached to ttyUSB10<o:p></o:p> [Mon Aug 14 10:21:58 2023] qmi_wwan 1-3.2:1.5: cdc-wdm1: USB WDM device<o:p></o:p> [Mon Aug 14 10:21:58 2023] qmi_wwan 1-3.2:1.5 wwan1: register 'qmi_wwan' at usb-0000:00:14.0-3.2, WWAN/QMI device,<o:p></o:p> <o:p> </o:p> <o:p> </o:p> Modems monitoring shows the modem being removed and added again with a different argument/number to access it from the cli: <o:p></o:p> /org/freedesktop/ModemManager1/Modem/1 [QUALCOMM INCORPORATED] 0<o:p></o:p> /org/freedesktop/ModemManager1/Modem/0 [QUALCOMM INCORPORATED] 0<o:p></o:p> <o:p> </o:p> (-) /org/freedesktop/ModemManager1/Modem/0 [QUALCOMM INCORPORATED] 0<o:p></o:p> (+) /org/freedesktop/ModemManager1/Modem/3 [QUALCOMM INCORPORATED] 0<o:p></o:p> <o:p> </o:p> Has anyone experienced this behavior before and have an idea of what could it be due to? And if so, is there a solution? <o:p></o:p> <o:p> </o:p> Thanks a lot in advance.<o:p></o:p> <o:p> </o:p> Best Regards, <o:p> </o:p> Melisa<o:p></o:p> </div> </body> </html>