Autoconnect backoff

[Sven Schwermer <sven svenschwermer de>]

Hi,

I have a device with cellular modem running a Linux-based OS with 
ModemManager/NetworkManager used for the connectivity management. 
Occasionally, the cellular connection breaks and it takes several 
connection attempts until the connection can be established again. 
Currently, we have autoconnect-retries=0 for our cellular connection so 
there are infinite retries. This, however, can cause significant system 
load if the ModemManager connect (dbus) calls fail immediately which 
occasionally happens.

As far as I understand, NetworkManager will attempt a new autoconnection 
attempt right away after the previous attempt failed. The only way of 
slowing this down is to set autoconnect-retries=1 which will cause 
NetworkManager to wait for 5 minutes between attempts. This wait 
duration seems to be fixed.

Is there a way to make NetworkManager perform a backoff (e.g. linear or 
exponential) between connection attempts? Are there any other ways to 
guarantee that the cellular modem is "always connected" without having 
NetworkManager to loop like crazy when a (re-)connection attempt fails?

Thanks and best regards,
Sven