Disconnect with non LTE capable provider

[Guido Günther]

Hi Aleksander,
On Wed, Feb 05, 2014 at 11:23:05AM +0100, Aleksander Morgado wrote:
> Hey Guido,
> 
> Adding Ben and Franko in CC, who should be interested in this issue.
> 
> > the umts modem in my laptop (Huawei ME906E) is LTE capable while my
> > provider isn't. Whenever the modem sees LTE it tries to upgrade the
> > connection and then disconnects:

[..snip..] 

> > (but it's the same using NM). I wonder how to disable LTE for these
> > situations and how to expose this in a user friendly way in NM since
> > this might be a rather common problem.
> 
> How about disallowing 4G temporarily? You could do:
>   mmcli -m0  --set-allowed-modes="2g|3g"

This results in

error: couldn't set current modes: 'GDBus.Error:org.freedesktop.ModemManager1.Error.Core.Unsupported: Cannot change modes: only one combination supported'

I tried this with 1.2.0 and current git master doesn't seem to have any
changes in this section.

> The ME906E should be happy with the latest SYSCFGEX changes I did for
> allowed/preferred mode switching.

It seems to support SYSCFGEX:

    AT ^SYSCFGEX=?
    ("00","03","02","01","99"),((2000004e80380,"GSM850/GSM900/GSM1800/GSM1900/WCDMA850/WCDMA900/WCDMA1900/WCDMA2100"),(3fffffff,"All Bands")),(0-3),(0-4),((800d7,"LTE1900/LTE2100/LTE2600/LTE1800/LTE900/LTEDD800/LTE850"),(7fffffffffffffff,"All Bands"))

I've not dug deeper into this yet since the WWAN connection in this
train is just too unreliable to do any proper readup on SYSCFGEX - what
an irony.

> Note that the connection settings for broadband devices in
> *NetworkManager* still have the 'allowed+preferred' modes
> configuration, *but* those are now ignored by MM >= 1.0. The correct
> way to handle capabilities and/or mode switching is not to add it as a
> per-connection configuration as it was before (we don't want to change
> those just before attempting a connection), but instead the UI should
> have some mechanism to change those values without even needing to
> fire a connection. I have my own ideas for GNOME3 to add this setup in
> the Network Settings, just not enough time to get them implemented.

Agreed. This should rather be per device than per connection.

Cheers,
 -- Guido