Can't see Yamaha Audio in Devices Available

[user-removed]

I have Spotify on my Samsung S6, and my laptop.  Both devices can be seen in the Devices Available when playing music.  However my Yamaha RX-A3040 is not visible on either my laptop or my phone.  We also have an S5 and and S4 in the house, and neither of these can see the Yamaha unit as an available device. 

However a friend was here with an iPhone and was able to see the Yamaha and play music through it.  

What do I need to do to be able to play my music on the audio system?  (I do have a premium account)

[Daniel]

Can you try rebooting your router?

[user-removed]

I've rebooted the router and the Yamaha.  I've uninstalled Spotify and reinstalled on all my devices.  I've checked that the phone and Yamaha have the latest firmware.  Still no joy.

[Daniel]

Please read the guide linked below for details on the most common issues and how to fix them. Usually a clean install is the first step to take and resolves most of the usual issues; the guide details the steps to take to ensure a full 'clean installation' is achieved - This includes checking redundant folders and a REBOOT!

[COMPLETE GUIDE] How to fix most Android issues

[user-removed]

Thanks for the link.  Unfortunately none of these resolve the issue.

I have since tried logging on to Spotify with a friend's login, using my phone.  Using his login I am able to find and play Spotify music through the Yamaha sound system on my phone.  However when I use my own login on my phone the Yamaha is not showing in the devices available.

This tells me it's something to do with my Spotify account.  However I have checked and my account is showing as Premium.  So I am at a loss as to what to try next. 

It's clearly my account, but I can't tell what the difference is between my account and my friend's account.