VM install: "no default route was set"

VM install: "no default route was set" https://www.softaculous.com/board/index.php?tid=17417 <![CDATA[]]> https://www.softaculous.com/board/index.php?tid=17417&tpg=0#p51891
I am using Virtualizor on an Ubuntu 18.04 server with KVM virtualization.
I usually install the OS on all the VMs via ISO and I really have no problems during CentOS or Windows installations.

The only problem is while installing Debian or Ubuntu VMs via ISO, I receive an error in the installer saying "The network autoconfiguration was successful. However, no default route was set: the system does not know how to communicate with hosts on the Internet."

Do you have any tips to understand what is the problem?
Thank you very much.

Regards]]> Fri, 22 Jan 2021 17:42:57 GMT https://www.softaculous.com/board/index.php?tid=17417&tpg=0#p51891