Disconnection issues after long periods of inactivity

[José]

Hi,

this is an issue I am currently having on a Android system using the
manufacturer RIL, and although I have also seen it using linux and
modemmanger, is more of a general cellular network question.

When being inactive for a long period (~24 hours) seems like the
connection goes down. The connectivity seems lost (trying to load a
webpage of ping a domain fails) but the modem seems active and
connected. In this state, when pinging directly to an IP I get outputs
similar to the following:

PING 8.8.8.8 (8.8.8.8) 56(84) bytes of data.

>From 100.82.203.31: icmp_seq=1 Destination Host Unreachable

--- 8.8.8.8 ping statistics ---

1 packets transmitted, 0 received, +1 errors, 100% packet loss, time 0ms

Can any of you explain what exactly happens? Thanks