Ubuntu 20.04 Server "Losing" IP4 address

[Captain Skyhawk]

(Cannot figure out what package is causing this, so I'm filing it as a bug this way.)

What version of Ubuntu?

Ubuntu 20.04 LTS

What I expected to happen?

Normal behavior.

What happened instead?

I have several VMs running on a host, all running Ubuntu 18.04 LTS. To prepare for an eventual 20.04 upgrade, I upgraded one guest to Ubuntu 20.04.

Everything went smoothly, with no issues.

The next day, however, I try to ssh into the guest, and it is not responding.

I use virt-manager to show a console window to the guest directly. Everything seems fine, but when I do "ifconfig", there is no IPv4 address listed (the "inet" line is simply not there, and there is only an 'inet6' version left). I do an "ifdown eth0 && ifup eth0", and the IPv4 address is listed again.

Just to see what's going on, I add the following line to cron:

*/5 * * * * (/bin/date && /sbin/ifconfig eth0) >> /home/webuser/log/ifconfig.output

I check the output later on, and I see that the IPv4 address was being successfully returned by the ifconfig command, until the 9AM run of this cron command, and then, the IPv4 address is gone again.

Any ideas? This behavior is only happening on the guest running 20.04 -- the 18.04 guests are unaffected.

[Ubuntu Foundations Team Bug Bot (crichton)]

Thank you for taking the time to report this bug and helping to make Ubuntu better. It seems that your bug report is not filed about a specific source package though, rather it is just filed against Ubuntu in general. It is important that bug reports be filed about source packages so that people interested in the package can find the bugs about it. You can find some hints about determining what package your bug might be about at https://wiki.ubuntu.com/Bugs/FindRightPackage. You might also ask for help in the #ubuntu-bugs irc channel on Freenode.

To change the source package that this bug is filed about visit https://bugs.launchpad.net/ubuntu/+bug/1884104/+editstatus and add the package name in the text box next to the word Package.

[This is an automated message. I apologize if it reached you inappropriately; please just reply to this message indicating so.]