> > How is the initial-attach-ip-type decided in the NM MR you shared? I've seen > in a network in New Zealand where initial-attach-iptype has to be IPV4 and > then it can be changed to IPV4V6 during connection establishment. >
I assume this could happen if the APN used during connection is different to the one used during initial attach? But this is definitely interesting; do you happen to have debug logs of MM on that setup to confirm your assumption? > Also, modem might have already gone through registration process before > "--3gpp-set-initial-eps-bearer-settings" is called. So when are we supposed > to call "mmcli --3gpp-set-initial-eps-bearer-settings"? > Yes, the modem always boots and attempts to register in the network automatically, that's the default. For initial attach it would use whatever it had configured. If you're using a device that comes with carrier-specific configs, the default config may already be the correct one for you. If you are using a generic firmware, there could be no explicit initial attach APN configured by default, but the network may be fine with providing you the correct one during the initial attach. You will need to use "--3gpp-set-initial-eps-bearer-settings" if e.g. you're not able to automatically register in the network and you know for sure the network you're trying to attach is the expected one. ModemManager dumps some warnings when attach failures happen, and we should definitely try to update the DBus API to expose those there as well (see https://gitlab.freedesktop.org/mobile-broadband/ModemManager/-/issues/715) -- Aleksander
