Can't find local machines by hostname

I have a USG40, and all devices on my network connect via DHCP. DNS is configured with the USG40 IP as the first DNS server. Devices all have correct configuration, and show up properly in the DHCP table, along with their hostnames. I cannot, however, connect to or ping any device on the network via its hostname, only the IP address. Any ideas on what might be happening here?


#Biz_Feb_2020