Change WiFi network

[GLO72]

I had my hp envy 6000 printer connected downstairs to my WiFi. I have moved it upstairs where I have an extension to the same WiFi but the network name has ..Ext added to the end.  My printer now says it's not connected to the internet. Im trying to put it in set up mode as I think that's what I need to do to connect it to the extension and I'm following this, but pressing the WiFi button on the back is doing nothing:

Use the Wireless button on the back of your printer to restore Wi-Fi setup mode.

1. On the back of the printer, press and hold the Wireless button 

    for five seconds.

   Note: 

   Your control panel might look different than the following example, but the steps are the same.

2. Wait for the Status light to turn purple.

3. Within two hours, return to the app or software to find and add 

[BeemerBiker]

This can be complicated and you may need to contact your ISP or register and ask for help on the ISPs forum

I think you have a flex system:  Repeaters and / or Wi-Fi boosters.

Either the main router or the repeater must be setup so that each band (2.4, 5 or 6ghz) has a different name or SSID.  In addition the IP address for the printer needs to come from a fixed or reserved list so that the printer gets the same IP address every time it is powered up or wakes up from sleep.