DNS problem with Algorand Server on Ubuntu 20.04

General
4

is not normal. Are you on your personal network or a company network with some firewall/proxy?

Can you try to disable DNSSec? Option DNSSecurityFlags in config.json (Node configuration settings - Algorand Developer Portal)
Concretely, update the file $ALGORAND_DATA/config.json (assuming $ALGORAND_DATA is your data directory with the file genesis.json) so that it looks like:

{
    "DNSSecurityFlags": 0,
    ...
}