I have a problem. When my ubuntu 20.04 start, network works ok but, after 5 minutes, it disconnects but I don't know why. I have checked the logs but I only see that the network goes from global to local and only works again when I unplug the wire and plug it back in.

No command works to bring up the interface again (systemctl) and either doesn't work by deactivating and activating the network again in graphic mode. ONLY works again if I unplug de wire and plug it back again.

I would like to know why this is happening, but my question is if you know if there is any command that simulates the unplug of the network wire.

Thank you.