Using wireless printer and chromecast on wifi extender

I am using a TP Link WiFi AV500 powerline range extender. It works really well, but I have a problem when using my wireless printer or Google chromecast. The extender routers are cloned to the main router, but the only way I can get the chromecast or wireless printer to work is to disable the extenders (presumably to ensure both devices are going through the same router?).

Any thoughts on why this is and how it can be resolved? Does the chromecast/printer think the routers are different networks, even though cloned?

Thanks
NJF