You can see a lot of good information for debugging and fixing errors on your Ubuntu server with journalctl and dmesg
journalctl --since "1 days ago"
journalctl --since "10 hours ago"
journalctl --since "12 hours ago" -p 3 -x --utc --no-pager
dmesg | less
dmesg -H --time-format iso| less
Resources:
https://unix.stackexchange.com/questions/50098/linux-network-troublesho…