Usually when hotels close past a certain time you can use a secondary entrance with your keys/card or at most call. Most hotels have a desk open 24h so this doesn’t even apply.
Also, I really don’t think Italians are generally rude. People are friendly, but also loud and warm, which often can be misunderstood. Assholes exist, obviously.
Nftables is the modern iptables FYI. Linux firewall.