RPi4 is not detected by the modem after a certain time (ethernet connection)

Question

I try to use a RPi4 B as a server (to setup netxcloud, PiHole, etc). To do this I connect it to the modem via ethernet connection as showed in this picture :

At first it works, the RPi is detected as router by the modem :

But then after some hours, the RPi seems to no be detected by the modem and the ethernet LEDs are turned off :

I need to reboot the RPi4 to get the ethernet reconnected to the modem.

I don't know much about network so I don't know if the problem is linked with the RPi itself (maybe the ethernet goes to a sleep mode after a certain time) or the modem.

Some of you have any idea how I could solve this problem so that I can run my RPi4 24/24h ?

Answer 1

Sorry to say this, but it looks like a quirk of your "modem". If it is managed remotely by your provider (I assume you didn't create a guest network, did you?) there may be little you can do.

Perhaps the connection times out if it's inactive. Check the settings of your box if you have access to them. Alternatively, try setting up a program which will keep sending data from your Pi. Something as trivial as ping -i 60 google.com ought to do.