can fsecure protect from network attacks

Denial of service attacks are typically not used against home computers. We don't have any specific protection against those, but of course the firewall by default blocks incoming packets.

DeepGuard offers some protection against 3rd party software vulnerabilities, like buffer overrun exploits.

We have no specific protection against ARP spoofing attacks. They are not a big threat to home users since the attacker must be in the same local network. If you are afraid of ARP spoofing for man-in-the-middle attacks, then the best advice is to always use HTTPS and verify that the certificates are good.