I am using Ubuntu as my home router and since migrating from Funtoo/Gentoo, I noticed I periodically have connection drops whereas I did not before. Looking further at the logs, I see my external interface going down right @ the T1 time (half of the DHCP lease).
I am using netplan to configure my system with systemd-networkd as the dispatcher.
I thought that I could mark the connection as critical via /etc/systemd/networkd.conf:
[DHCP]
CriticalConnection=true
UseDNS=false
UseNTP=false
However, that doesn't appear to do anything.
I am referencing the documentation here: http://manpages.ubuntu.com/manpages/bionic/man5/systemd.network.5.html
I placed the file in the wrong place, it needed to be put here:
/etc/systemd/network/*.network
Where * can be whatever you like. For me, I named it default (default.network).