I see you mention that you tried using the speaker both wireless and wired, are you using the same controller you were using at work? (if so, what controller/version of iOS/Android is it?) ... and did you factory reset the speaker already, or not?

Also are you adding the speaker to an ‘existing’ Sonos system at your home?

Wow! That was a fast response! Thank you

Directly after writing my message, I tried all steps again and it connected. Now it has disconnected again
 

1.Yes, I was using the same controller, but I also reset it numerous times.

2. I’m currently using Version 11.2.4
3. I’ve reset the app
4. No, I didn’t have an existing Sonos system at home.

Thank you in advanced

I’m guessing you did manage to get the speaker setup, post factory-reset?... If that is the case, can you wire it back to your router temporarily and open the Sonos App.

If not, then wire it again and setup the "factory reset” speaker whilst it is wired.

When the speaker (re)appears and is setup in the App, goto "Settings/System/Network/Wireless Setup” and choose to add your current Home routers 2.4ghz WiFi credentials (SSID/Password) (NB: they are cAsE SenSitive) to this section of the App.

After a few seconds you should be able to un-cable the speaker and all being well, it should then continue to run on your Home routers WiFi signal. 

Ok. I will try this and post here with the outcome. Thank you