Comment 7 for bug 583728

Dun with network manager has now been broken for a few years. We have passed from hard kernel crashes on attempts to use it to the current situation where the functionality is advertised and simply not working.

Now, I am on trusty and I do not know if my case is exactly the one mentioned in this bug.

In my case, it is modemmanager to simply ignore the rfcomm0 device.

In fact, if I set up the device and then query modem manager with mmcli, modemmanager says "no modem found". If I run modemmanager in debug mode, it says that it cannot find the parent device of rfcomm0, so it skips it.

Looks like a kernel bug. On LKML there are posts about the kernel failing to parent the rfcomm devices, causing regressions in modemmanager. Maybe the ubuntu kernel maintainers could take a look into it and backport relevant fixes to the ubuntu 3.14 kernel (if there are any).

But, even better, I really think that bluetooth DUN should be disabled altogether in networkmanager in ubuntu, until the kernel, modemmanager and networkmanager can support it properly. It has now been in a broken state for at least 3 (if not 4) ubuntu releases. If it is not working, at least do not tempt users to try it.