Software firewalls often block the mDNS traffic preventing you from using the .local domain to address devices on your local network. Some linux systems ship with the firewall enabled by default and with no built in exceptions for mDNS.
On systems that use UFW:
sudo ufw allow mdns
If you are running a system that ships with firwewalld (such as Fedora or Suse):
sudo firewall-cmd --permanent --add-service=mdns
sudo firewall-cmd --reload