There is an IP Address on my LAN Client List that I can't account for.  I just took an audit of all my network devices and I can't account for this IP Address! So I blocked it on the ER605 Firewall. Then all of a sudden we have no access to the Internet! I know the MAC Address and IP Address of my WiFi 6 access point and that's the one that is supposed to be our gateway for all our LAN devices but this un-accounted device with the IP address that I blocked caused everything to stop our Internet connection from the WiFi side!

The IP Address that it acquired from the ER605's DHCP is 192.168.5.104 (I have a DHCP range of 100 - 254) with a Device Name of "ESP_3C661B" and its MAC is 84-F3-EB-**-**-**.  The vendor for 84-F3-EB is Espressif, Inc. from Shanghai, China.

What is this device?  I know it is NOT physical because I have accounted for all my network devices. This may be a malicious virtual device that is controlling all our LAN traffic.  What can I do?

Thanks for any advice here.