@gaz7 Was thinking about your problem more and wanted to see something. If you can go into the deco app and from the network tab look at the top left for three lines click them and then look for...

@gaz7 What about turning on the guest network and connecting the printer to the WiFi that way?

@marounie Please see the following post from a member of the tp-link staff about the web ui https://community.tp-link.com/us/home/forum/topic/759890?replyId=1584350 Thank you

@gaz7 Do you know if your printer has a WPS button on it?

@matthewadelaide Would you mind looking up some info for me? On the phone you first tried that didn't work go into the deco app and on the Network tab click on the row of three lines at the top left...

@David-TP