If I reboot the hubitat hub I can telnet to the receiver and all the commands work. but I'm not able to telnet after trying from Hubitat. The logs stated the command ran but the status doesn't change and no changes on the receiver.
My Denon receiver only allows a single telnet connection while my Onkyo allows multiple. Your Pioneer May be the same where once your HE hub establishes a connection, you are not able to connect from another device. Rebooting the HE kills the connection, thus opening up ability to connect from another device.