'port forced close' after failed ppp

[Colin Helliwell]

> On 07 March 2017 at 13:50 Aleksander Morgado <aleksander at aleksander.es> wrote:
> 
> On Tue, Mar 7, 2017 at 1:26 PM, Colin Helliwell
> 
> <colin.helliwell at ln-systems.com> wrote:
> 
> > > Mar 7 10:05:25 wg2 daemon.debug pppd[944]: sent [IPCP ConfReq id=0x1 <ms-dns1 0.0.0.0> <ms-dns2 0.0.0.0>]
> > > Mar 7 10:05:25 wg2 daemon.info ModemManager[896]: [1488881125.484324] [src/mm-port-serial.c:1294] mm_port_serial_open(): (ttyMux0) device open count is 2 (open)
> > > Mar 7 10:05:25 wg2 daemon.info ModemManager[896]: [1488881125.484745] [src/mm-port-serial-at.c:459] debug_log(): (ttyMux0): --> 'AT+CGACT?'
> > > Mar 7 10:05:25 wg2 daemon.info ModemManager[896]: [1488881125.513270] [src/mm-port-serial-at.c:459] debug_log(): (ttyMux0): <-- '+CGACT: 1,0OK'
> > 
> > *HERE*
> > 
> > > Mar 7 10:05:25 wg2 daemon.info ModemManager[896]: [1488881125.514773] [src/mm-base-bearer.c:172] load_connection_status_ready(): connection status loaded: disconnected
> > > Mar 7 10:05:25 wg2 daemon.info ModemManager[896]: [1488881125.515912] [src/mm-port.c:94] mm_port_set_connected(): (ttyMux1): port now disconnected
> > > Mar 7 10:05:25 wg2 daemon.info ModemManager[896]: [1488881125.516973] [src/mm-iface-modem.c:1431] __iface_modem_update_state_internal(): Modem /org/freedesktop/ModemManager1/Modem/0: state changed (connected -> registered)
> 
> That is the standard connectivity check done by MM using AT+CGACT?.
> Looks like the modem is reporting PDP context 1 (the one you used for
> connecting) is disconnected (state 0)?
> 

Yes, I see what you mean. Now, [my] confusion is: the PDP is (I believe) being activated on ttyMux1 - the virtual port which is set as the PPP port. But the connectivity check is being done on ttyMux0 - the primary port.
So, is MM expecting to be able to check the connectivity of the PPP port via the primary? That would make sense, I guess - but I'm wondering (to myself) how the modem's multiplexer deals with this i.e. whether it sees a distinction between which port the AT+CGACT? is done on.
BTW - is the connectivity check new since 1.6? 

I'm now back at a previous working state, by exposing only one port to MM. With this I can get ppp connection, albeit with connectivity check and signal quality failing because the port is in use.
So I need to figure out whether I can get MM to be able to monitor the connection on ttyMux1, using ttyMux0. 
Surely ought to be possible - otherwise what's the point in having the query command if it won't fetch you the answer for the other port?! Might be something I need to dig into at the modem Mux's end of things. If I'm understanding things right, that is. e.g. Is there a difference between a 'PDP [#1] context activation' and the 'ATD*99***1##' ?