There are many services in your local network, which are un-encrypted. Any basic protocol that is in the lower layers required to run the infrastructure like AR

There are many services in your local network, which are un-encrypted. Any basic protocol that is in the lower layers required to run the infrastructure like ARP, DHCP, DNS, and alike. Then there are also higher layer protocols, which are un-encrypted like SMB, AFP, NFS, and alike. Many IoT devices, like your Cisco Phone talks TFTP at startup. That is the reason why we have/had WEP, WPA, WPA2 to allow a local infrastructure to have the very same trust like physical cables.