Hello, We have some embedded devices deployed in the field using a huawei E173s-1 modem. We're having some issues where connectivity stops working randomly, after 1-3 weeks of uptime.
First, there's a PPP disconnection. Then there's a few loops of this error for 1-2 seconds, rather fast: failed to connect modem: Couldn't connect: cannot keep data port open.Could not open serial device ttyUSB0: reopen operation in progress Afterwards, there are 10 attempts of reconnecting, with "at port timed out X consecutive times" errors. After 10 attempts, ModemManager gives up permanently, and never tries again to bring the device back up. (tty/ttyUSB0) at port timed out 10 consecutive times, marking modem '/org/freedesktop/ModemManager1/Modem/0' as invalid A few hours later, when we could get onsite, restarting ModemManager and NetworkManager brought the modem back online with no issues (with no unplug/replug/powercycle of the modem or the Linux board.) This means the modem is not irreversibly crashed/failed, so I think this is a software issue that should be fixable. Unfortunately, ModemManager was set to INFO log level because we though DEBUG was too verbose. We have set DEBUG log level, so the next time it happens we will have more logs. I would really appreciate any input you may have on how to solve this. - I thought of patching out the "max 10 timeouts" limit, so ModemManager keeps retrying indefinitely. Is this a good idea? - What can I try so next time this happens we can get more info on the issue? (besides debug log level) - Any recommendations in general on how to ensure the device is always connected? Any config knobs to tweak? We've been thinking of adding a "if no internet during 10 minutes, powercycle everything" watchdog, but that feels like giving up on getting this working properly. Thanks in advance! Dario --- Logs of the time of failure: https://gist.github.com/Dirbaio/bdea5235b832ee12d4b56caf7576fe3d Output of mmcli -m 0: https://gist.github.com/Dirbaio/13c97d9ec508faba0829ce9de0cf79de lsusb output: https://gist.github.com/Dirbaio/0e58a51fd551272f92530f96c612b8c6 Relevant software versions: - ModemManager 1.10.0 - NetworkManager 1.16.0 - Linux 5.0.5 - pppd 2.4.7
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