ModemManager - not detecting when no longer routable/pingable

I was hopeful that this fix was going to be the ultimate fix but it doesn't take care of the case where ModemManager shows everything as connected as if nothing happened but no pings or traceroute through the WAN is working unless rebooted. I don't know if I need to use foolsm or some type of ping/poll solution to address this condition.

IMHO, the fix only takes care of an issue, in case modemmanager detects a disconnect. But how should it detect an issue, in case modem simply hangs, for example ? (Which I have seen in real world.)
BTW, this was always my critics against use of modemmanager. I prefere (and advocate) a solution based on pings or similar, to catch all possible (and theoretically impossible :slight_smile: issues.

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does modem manager serial interface not periodically check for connection and response from the modem?
I thought that was it's purpose.

I admit I had issues with 3g/ 4g connection with every method in OpenWrt and have used an external device for my modem needs.

I was going to retry with this new patch to see if problems were resolved.

AFAIK, modemmanager reacts on certain events, detected by various means. I.e. change of IP, initiated by the carrier.
Author(s) of modemmanager invited, to correct me, if applicable. A general flaw to such a design is the (sad) fact, that sometimes events get lost. Or not all reasons of broken connections are signalled using events. Like a modem hang. Active probing the connection via ping etc. has the disadvantage, to generate traffic, to be payed for. But catches all reasons of disconnection. mwan3 can be a vehicle to detect such a disconnection and initiate auto-failover, if available. Without failover possibility, there are simpler tools. Even a custom script to be done, tailored to the installed modem for recovery, if possible. At least, this is the KISS solution I use for industrial, commercial systems.

I use Watchcat to reestablish connections with my external modem if the connection has issues.
Restarting the wan port connection to the external modem reestablishes connection on an upstream IP change.
I don't see why it would not work with watchcat as long as it waits long enough to establish a connection before re attempting a reboot, causing a restart loop.
but it also must know that a connection has been established before it starts, as endless restarting of an interface won't help all situations.

It seems like the rooter project seems to have this sorted, can we not bring over some of their tools to vanilla OpenWrt ?