Problem with reconnecting when using Ericsson H5321 modem and Aero2 BDI network

[Mateusz P]

Hi,
I have a problem with modemmangager 1.6.8-2ubuntu1 and 1.8.2-1.

Modem: Ericsson H5321.
Computer: Lenovo ThinkPad X230.
Network: Aero2 BDI (Polish, APN darmowy).

The network (according to obtained licence for using radio spectrum 
frequencies) is obliged to provide a service of a free Internet access 
with a few limits.
One of those limits is an automatic disconnection every (about) 1 hour. 
In order to access the Internet again one needs to reconnect and solve 
the Captcha.

The first problem with the mentioned modem is that the disconnection is 
not visible to the user - the Network Manager works as if the connection 
would be still active - the Network Manager shows the connection as 
still active and one needs to disconnect manually as there is no 
Internet access.
The problem is there is no way to reconnect to the network as after 
disconnecting Network Manager only flashes connecting icon and shows 
disconnected icon.
After restarting Network Manager or modemmanager services the problem 
still persists. It can be solved by suspending or rebooting the computer.
The problem exists on both Linux Mint 19 Xfce (1.6.8-2ubuntu1) and 
Manjaro 17.1.12 OS-es (1.8.2-1).

Related logs (dpkg -l, mmcli, modemmanager, NetworkManager): 
https://gist.github.com/mp107/238e6d745770a4f666902fd45a8de95e
Timestamps of some of the trials of reconnecting to the network: 
1541701353, 1541701417.

Best regards,
Mateusz