Thank you for using the Support Forum. The 78xx can only have one IP address so it would depend on how your network(s) are set up. If both networks can work with the IP assigned to the printer then yes. If this does not answer your question please consider contacting your support centre for further assistance.
Having actually attempted this it is not possible. When enabling the wi fi the wired ethernet is disabled and vice versa. If someone has done it otherwilse I would like to know how as it would be a good option in certain atmospheres.