Dell OptiPlex 960 desktop with Win 10 installed.

Installed Software from CD for Dell E525W printer when connected via USB.  I was able to print when connected with USB.

I removed the USB cable, set up Wifi on the printer by entering the WiFi password correctly but control panel -> devices and printers is showing the printer as Offline.

The blue Wifi button on the printer is glowing a steady blue and the LCD panel is showing ip address so I assume the printer is connected to Wifi.

My wireless adapter is: Realtek RTL8192EU Wireless LAN 802.11n USB 2.0

The driver for it is up to date.

Any ideas on how to resolve it?

(I did have Win 8 previously installed and was able to print over Wifi to a Kodak printer so I don't think it is a hardware fault).