'port forced close' after failed ppp

[Colin Helliwell]

> On 08 March 2017 at 14:38 Aleksander Morgado <aleksander at aleksander.es> wrote:
> 
> On Wed, Mar 8, 2017 at 3:08 PM, Colin Helliwell
> 
> <colin.helliwell at ln-systems.com> wrote:
> 
> > But this brings me back (in a round-the-houses way!) to my original question: when the PPP fails, for example with the ports assigned the right way round, but on 'faulty' SIM1, why is the PPP port getting "forced closed" and then unable to be retried?
> > My concern being if PPP fails for an external reason e.g. at the remote end, then it can't retry?
> 
> Forgive my bad memory here. I think the HUP that triggers the "forced
> close" in the TTY shouldn't be received by ModemManager, it should be
> processed by pppd, which is the one that handles that disconnection.
> pppd resets all modem control lines on exit, IIRC. I recall a similar
> problem when playing with the NetworkManager integration, which is the
> one that would call pppd to establish the connection; I think I solved
> it just by making sure pppd is completely closed before Disconnect()
> is called for the modem in ModemManager (i.e. so that pppd could
> recover the original state of the control lines before passing the
> control of the TTY to MM through the Disconnect() call). Does that
> make any sense at all?
> 

Ermmm, some...!
However I've found that the same thing is happening even when the PPP is successful - MM is getting the "unexpected port hangup!" when I close PPP. I'm doing:
  mmcli -m 0 --enable
  mmcli -m 0 --simple-connect="apn=wap.vodafone.co.uk"
  pon
  ... success ...
  poff
  mmcli -m 0 --simple-disconnect

Then trying again to connect fails with 'forced close'