Songs keep restarting when played via Denon Heos multiroom speaker system

[Tobey81]

Plan

Premium

Country

Germany

Device

Samsung Galaxy 7, with Denon HEOS 1 and HEOS 5

Operating System

Android

My Question or Issue

Dear all, I hope to receive assistance here since Denon insists that the below must be a software (rather than hardware) issue. Thanks a lot in advance!

When playing songs via Spotify through my Denon Heos system (1x Heos 1 + 1x Heos 5), every other song restarts from the beginning. This is extremely annoying, esp. when listening to e-books. The song simply starts over after almost reaching the end.

I have since: 

- Tested this from my Galaxy S7 phone, another Galaxy S6 phone, my Windows laptop - occurs on all devices,

- Tried with both speakers bundled together and playing from them separately - occurs with both setups,

- Updated Android,

- Reinstalled the latest Spotify version,

- Reset my router, 

- Updated my Denon Heos system, 

- Reset the Denon Heos system.

I have found four threats addressing this problem, however none seems to be solved yet.

Thank you very much in advance!

Toby

Related threats:

1) https://community.spotify.com/t5/Other-Partners-Web-Player-etc/Songs-restarting-on-Deon-HEOS-control...

2) https://community.spotify.com/t5/Android/Song-restart-randomly/m-p/4477522

3) https://community.spotify.com/t5/Desktop-Mac/Spotify-connect-randomly-restart-current-song/m-p/44819...

4) https://community.spotify.com/t5/Android/Song-restarts-when-it-has-played-aprox-70/m-p/1528027