Devices not recognizing eachother

[Antonycml]

Hi everyone. I have fairly recently started using Spotify so please forgive my inexperience! I have just found my account is not being recognized on my Yamaha RX V675 amp from all my devices, iPad, iPhone and laptop. I am a premium member and was using my iPad primarily to stream music to the amp. All 3 devices were being recognized by the amp and could stream music through my wifi network. Yesterday for some reason all three devices are not being recognized by the amp but recognize each other. My iPad is the main device I like to use to control streaming of music to the amp via the app downloaded, but now it does not recognize the amp as a device.
I know the amp us working ok because my partner on his iPad can connect to the amp and They recognize each other as devices exist !
I have tried deleting and reloading the app on my iPad, logging out and in again but the device is not being recognized. As I can see the amp is working ok with another iPad and account, and it was working ok with my iPad and iPhone originally, it can now only be a problem with my account ? Any suggestions please. If I can't resolve this issue I don't see any point in me continuing to pay for premium subscription if I can't use it to stream music my amp.
Thanks for any help
Antony