Broadband Modem DW5932e (X62 Snapdragon) partially workin on Linux (Dell Precision 3591)

Hi all here, 

I got a brand new Precision 3591 for Christmas (it's for professional use :)) and I successfully installed Linux and got everything working, except the Modem (it's a X62 Snapdragon, with esim support)

I currently got here: 

- modem is recognized and its status can be displayed via mmcli 

- the fcc unlock procedure has been setup properly (https://github.com/foxconn-pc/fii_linux)

- I correclty setup and unlock the SIM, and use it to connect 

- I can connect to my broadband provider 

- I can then observe some data being sent to the air, but nothing can be received. <== THIS IS THE PROBLEM 

- I also tested with another SIM from another telco , does the same thing.

- I did a BIOS update using the "remote method" 

Anyone tried to get a X62 Modem working on Linux ?

Informations for future debugging :

- modemmanager-1.22.0-1

- libmbim-1.30.0-1

- libqmi-1.34.0-2

No really useful logs via journalctl....

Once connected , I get the following information from mmcli: 

# mmcli -m 0 

 ------------------------------------
 General   |                    path: /org/freedesktop/ModemManager1/Modem/0
           |               device id: xxxxxxxxxxxxxxxxxx
 ------------------------------------
 Hardware  |            manufacturer: foxconn
           |                   model: DELL Snapdragon X62
           |       firmware revision: FDE.F0.3.0.1.1.GC.002
           |                          050  
           |          carrier config: GCF
           | carrier config revision: 0A000802
           |            h/w revision: DELL Snapdragon X62
           |               supported: gsm-umts, lte, 5gnr
           |                 current: gsm-umts, lte, 5gnr
           |            equipment id: 356566811514173
 ------------------------------------
 System    |                  device: /sys/devices/pci0000:00/0000:00:1c.0/0000:57:00.0
           |                 physdev: /sys/devices/pci0000:00/0000:00:1c.0/0000:57:00.0
           |                 drivers: mhi-pci-generic
           |                  plugin: foxconn
           |            primary port: wwan0mbim0
           |                   ports: wwan0 (net), wwan0at0 (at), wwan0mbim0 (mbim),  
           |                          wwan0qcdm0 (ignored)
 ------------------------------------
 Status    |                    lock: sim-pin2
           |          unlock retries: sim-pin (3), sim-pin2 (3)
           |                   state: connected
           |             power state: on
           |             access tech: lte
           |          signal quality: 35% (cached)
 ------------------------------------
 Modes     |               supported: allowed: 3g; preferred: none
           |                          allowed: 4g; preferred: none
           |                          allowed: 3g, 4g; preferred: 4g
           |                          allowed: 3g, 4g; preferred: 3g
           |                          allowed: 5g; preferred: none
           |                          allowed: 4g, 5g; preferred: 5g
           |                          allowed: 4g, 5g; preferred: 4g
           |                          allowed: 3g, 5g; preferred: 5g
           |                          allowed: 3g, 5g; preferred: 3g
           |                          allowed: 3g, 4g, 5g; preferred: 5g
           |                          allowed: 3g, 4g, 5g; preferred: 4g
           |                          allowed: 3g, 4g, 5g; preferred: 3g
           |                 current: allowed: 3g, 4g, 5g; preferred: 5g
 ------------------------------------
 Bands     |               supported: utran-1, utran-4, utran-6, utran-5, utran-8, utran-2,  
           |                          eutran-1, eutran-2, eutran-3, eutran-4, eutran-5, eutran-7, eutran-8,  
           |                          eutran-12, eutran-13, eutran-14, eutran-17, eutran-18, eutran-19,  
           |                          eutran-20, eutran-25, eutran-26, eutran-28, eutran-29, eutran-30,  
           |                          eutran-32, eutran-34, eutran-38, eutran-39, eutran-40, eutran-41,  
           |                          eutran-42, eutran-43, eutran-46, eutran-48, eutran-53, eutran-66,  
           |                          eutran-70, eutran-71, utran-19, ngran-1, ngran-2, ngran-3, ngran-5,  
           |                          ngran-7, ngran-8, ngran-12, ngran-13, ngran-14, ngran-18, ngran-20,  
           |                          ngran-25, ngran-26, ngran-28, ngran-29, ngran-30, ngran-38, ngran-40,  
           |                          ngran-41, ngran-48, ngran-53, ngran-66, ngran-70, ngran-71, ngran-75,  
           |                          ngran-76, ngran-77, ngran-78, ngran-79
           |                 current: utran-1, utran-4, utran-5, utran-8, utran-2, eutran-1,  
           |                          eutran-2, eutran-3, eutran-4, eutran-5, eutran-7, eutran-8,  
           |                          eutran-12, eutran-13, eutran-14, eutran-17, eutran-18, eutran-19,  
           |                          eutran-20, eutran-25, eutran-26, eutran-28, eutran-29, eutran-30,  
           |                          eutran-32, eutran-34, eutran-38, eutran-39, eutran-40, eutran-41,  
           |                          eutran-42, eutran-43, eutran-46, eutran-48, eutran-66, eutran-71,  
           |                          ngran-1, ngran-2, ngran-3, ngran-5, ngran-7, ngran-8, ngran-12,  
           |                          ngran-13, ngran-14, ngran-18, ngran-20, ngran-25, ngran-26, ngran-28,  
           |                          ngran-30, ngran-38, ngran-40, ngran-41, ngran-48, ngran-53, ngran-66,  
           |                          ngran-70, ngran-71, ngran-75, ngran-76, ngran-77, ngran-78, ngran-79
 ------------------------------------
 IP        |               supported: ipv4, ipv6, ipv4v6
 ------------------------------------
 3GPP      |                    imei: xxxxxxxxxxxxxx
           |           enabled locks: sim, fixed-dialing
           |             operator id: 20810
           |           operator name: Prixtel
           |            registration: home
           |    packet service state: attached
           |                     pco: 0: (partial) '270480000000'
 ------------------------------------
 3GPP EPS  |    ue mode of operation: csps-2
           |     initial bearer path: /org/freedesktop/ModemManager1/Bearer/0
           |  initial bearer ip type: ipv4v6
 ------------------------------------
 3GPP 5GNR |               mico mode: unsupported
           |               drx cycle: unsupported
 ------------------------------------
 SIM       |        primary sim path: /org/freedesktop/ModemManager1/SIM/0
           |          sim slot paths: slot 1: /org/freedesktop/ModemManager1/SIM/0 (active)
           |                          slot 2: none
 ------------------------------------
 Bearer    |                   paths: /org/freedesktop/ModemManager1/Bearer/1