I'm seeing the same (or at least a highly similar) problem on Ubuntu 22.10:

    NetworkManager[1628]: <info>  [1718657963.8557] device (CC:21:19:DA:E8:EA): Activation: starting connection 'Gambit Network' (e2a0aeb8-c87f-4ac6-8972-1e0bfac16e91)
    NetworkManager[1628]: <info>  [1718657963.8558] audit: op="connection-activate" uuid="e2a0aeb8-c87f-4ac6-8972-1e0bfac16e91" name="Gambit Network" pid=1359709 uid=1000 result="su

    NetworkManager[1628]: <info>  [1718657963.8559] device (CC:21:19:DA:E8:EA): state change: disconnected -> prepare (reason 'none', sys-iface-state: 'managed')
    bluetoothd[1287905]: bnep0 connected
    kernel: bluetooth hci0:256 enxc403a8869e89: renamed from bnep0 (while UP)
    NetworkManager[1628]: <warn>  [1718657964.0945] device (CC:21:19:DA:E8:EA): ip-ifindex: ifname bnep0 not found
    NetworkManager[1628]: <warn>  [1718657964.0946] device (CC:21:19:DA:E8:EA): Error connecting with bluez: cannot find device bnep0
    NetworkManager[1628]: <info>  [1718657964.0946] device (CC:21:19:DA:E8:EA): state change: prepare -> failed (reason 'bluetooth-failed', sys-iface-state: 'managed')
    NetworkManager[1628]: <warn>  [1718657964.0952] device (CC:21:19:DA:E8:EA): Activation: failed for connection 'Gambit Network'
    NetworkManager[1628]: <info>  [1718657964.0955] device (CC:21:19:DA:E8:EA): state change: failed -> disconnected (reason 'none', sys-iface-state: 'managed')
    bluetoothd[1287905]: profiles/network/bnep.c:bnep_if_down() bnep: Could not bring down bnep0: No such device(19)

This happens when NetworkManager/Modemmanager connects to my phone for tethering via bluetooth.

This started happening somewhere in the last couple of weeks, while it worked fine before that. However, the connection now fails most of the the time, but if I retry a few (sometimes a dozen) times, it usually connects eventually. So maybe there is a race condition that has been present for a long time, but just became a lot more likely due some (possibly otherwise unrelated) change in timing or otherwise.


Here's what it looks like when it does work:


    NetworkManager[1628]: <info>  [1718658216.0757] device (CC:21:19:DA:E8:EA): Activation: starting connection 'Gambit Network' (e2a0aeb8-c87f-4ac6-8972-1e0bfac16e91)
    NetworkManager[1628]: <info>  [1718658216.0758] audit: op="connection-activate" uuid="e2a0aeb8-c87f-4ac6-8972-1e0bfac16e91" name="Gambit Network" pid=1359709 uid=1000 result="s>
    NetworkManager[1628]: <info>  [1718658216.0759] device (CC:21:19:DA:E8:EA): state change: disconnected -> prepare (reason 'none', sys-iface-state: 'managed')
    bluetoothd[1287905]: bnep0 connected
    kernel: bluetooth hci0:256 enxc403a8869e89: renamed from bnep0 (while UP)
    NetworkManager[1628]: <info>  [1718658217.3531] device (CC:21:19:DA:E8:EA): ip-ifname: interface index 0 renamed ip_iface (15295) from 'bnep0' to 'enxc403a8869e89'
    NetworkManager[1628]: <info>  [1718658217.3531] device (CC:21:19:DA:E8:EA): state change: prepare -> config (reason 'none', sys-iface-state: 'managed')
    NetworkManager[1628]: <info>  [1718658217.3589] device (CC:21:19:DA:E8:EA): state change: config -> ip-config (reason 'none', sys-iface-state: 'managed')
    NetworkManager[1628]: <info>  [1718658217.3603] dhcp4 (enxc403a8869e89): activation: beginning transaction (timeout in 45 seconds)

From the looks of this, it actually seems that NetworkManager sometimes catches and sometimes misses the rename, so maybe my issue is an issue in NetworkManager.



In any case, for anyone else that runs into something like this, as a workaround I just disabled interface renaming in udev using the following rule (which, by setting a NAME prevents /usr/lib/udev/rules.d/80-net-setup-link.rules from renaming the interface).

    $ cat /etc/udev/rules.d/10-local-bluetooth-no-rename.rules 
    SUBSYSTEM=="net", ACTION=="add", KERNEL=="bnep0", NAME="bnep0"