DLNA for Music with Marantz SR7007 leads to errors

Hi,
when I want to start playback via DLNA for some FLAC music files over my Marantz SR7007 I am getting an error in the Logs. But I do not get what is actually wrong. Is a more specific profile needed?

Anyone any ideas?

[2020-01-19 13:39:27.052 +01:00] [INF] WS "http://jellyfin.example.com/socket?api_key=826b625e45a541bb85b0a5c2f8ca3760&deviceId=TW96aWxsYS81LjAgKFgxMTsgVWJ1bnR1OyBMaW51eCB4ODZfNjQ7IHJ2OjcyLjApIEdlY2tvLzIwMTAwMTAxIEZpcmVmb3gvNzIuMHwxNTc5NDM3NTUyMDQ4". UserAgent: "Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:72.0) Gecko/20100101 Firefox/72.0"
[2020-01-19 13:40:58.146 +01:00] [ERR] AcceptWebSocketAsync error
System.Net.WebSockets.WebSocketException (0x80004005): The remote party closed the WebSocket connection without completing the close handshake. ---> System.Net.WebSockets.WebSocketException (0x80004005): The remote party closed the WebSocket connection without completing the close handshake.
   at System.Net.WebSockets.ManagedWebSocket.ThrowIfEOFUnexpected(Boolean throwOnPrematureClosure)
   at System.Net.WebSockets.ManagedWebSocket.EnsureBufferContainsAsync(Int32 minimumRequiredBytes, CancellationToken cancellationToken, Boolean throwOnPrematureClosure)
   at System.Net.WebSockets.ManagedWebSocket.ReceiveAsyncPrivate[TWebSocketReceiveResultGetter,TWebSocketReceiveResult](Memory`1 payloadBuffer, CancellationToken cancellationToken, TWebSocketReceiveResultGetter resultGetter)
   at System.Net.WebSockets.ManagedWebSocket.ReceiveAsyncPrivate[TWebSocketReceiveResultGetter,TWebSocketReceiveResult](Memory`1 payloadBuffer, CancellationToken cancellationToken, TWebSocketReceiveResultGetter resultGetter)
   at Emby.Server.Implementations.SocketSharp.WebSocketSharpListener.ProcessWebSocketRequest(HttpContext ctx)
[2020-01-19 13:40:58.657 +01:00] [INF] WS "http://jellyfin.example.com/socket?api_key=ada6bcf679de4bf9869d3fd418c803b0&deviceId=TW96aWxsYS81LjAgKFgxMTsgVWJ1bnR1OyBMaW51eCB4ODZfNjQ7IHJ2OjcyLjApIEdlY2tvLzIwMTAwMTAxIEZpcmVmb3gvNzIuMHwxNTc4ODU0MzY5ODMx". UserAgent: "Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:72.0) Gecko/20100101 Firefox/72.0"
[2020-01-19 13:40:59.861 +01:00] [INF] Getting image size for item "PhotoAlbum" "/storage/metadata/library/ce/ce69fb0e082cc36daa0e356c4ff17c3e/folder.jpg"
[2020-01-19 13:41:00.030 +01:00] [INF] Getting image size for item "PhotoAlbum" "/storage/metadata/library/f4/f40c373b54ff8aa6f45d1c005dad689a/folder.jpg"
[2020-01-19 13:41:00.205 +01:00] [WRN] HTTP Response 200 to "2001:a61:3574:601:f880:cd7c:fbdd:d203". Time (slow): 0:00:00.8516338. "http://jellyfin.example.com/Items/b0ef1a4b86d0f7b40a16e243a573658c/Images/Backdrop/0?tag=f641a0568eb9c8e0e9630c408852dd97&maxWidth=1700&quality=70"
[2020-01-19 13:41:00.443 +01:00] [ERR] Error processing request: "A task was canceled."
[2020-01-19 13:41:00.457 +01:00] [ERR] Error processing request: "A task was canceled."
[2020-01-19 13:41:00.482 +01:00] [ERR] Error processing request: "A task was canceled."
[2020-01-19 13:41:00.495 +01:00] [ERR] Error processing request: "A task was canceled."
[2020-01-19 13:41:01.152 +01:00] [ERR] Error processing request: "A task was canceled."
[2020-01-19 13:41:01.159 +01:00] [ERR] Error processing request: "A task was canceled."
[2020-01-19 13:41:01.189 +01:00] [ERR] Error processing request: "The operation was canceled."
[2020-01-19 13:41:06.220 +01:00] [ERR] Error processing request: "A task was canceled."
[2020-01-19 13:41:06.269 +01:00] [ERR] Error processing request: "A task was canceled."
[2020-01-19 13:41:06.279 +01:00] [ERR] Error processing request: "The operation was canceled."
[2020-01-19 13:41:06.280 +01:00] [ERR] Error processing request: "The operation was canceled."
[2020-01-19 13:41:06.296 +01:00] [ERR] Error processing request: "The operation was canceled."
[2020-01-19 13:41:07.934 +01:00] [ERR] Error processing request
System.ArgumentNullException: Value cannot be null.
Parameter name: baseUrl
   at MediaBrowser.Model.Dlna.StreamInfo.ToUrl(String baseUrl, String accessToken)
   at Emby.Dlna.PlayTo.PlayToController.CreatePlaylistItem(BaseItem item, User user, Int64 startPostionTicks, String mediaSourceId, Nullable`1 audioStreamIndex, Nullable`1 subtitleStreamIndex)
   at Emby.Dlna.PlayTo.PlayToController.SendPlayCommand(PlayRequest command, CancellationToken cancellationToken)
   at Emby.Server.Implementations.Session.SessionManager.SendMessageToSession[T](SessionInfo session, String name, T data, CancellationToken cancellationToken)
   at Emby.Server.Implementations.Session.SessionManager.SendPlayCommand(String controllingSessionId, String sessionId, PlayRequest command, CancellationToken cancellationToken)
   at Emby.Server.Implementations.Services.ServiceExecGeneral.GetTaskResult(Task task)
   at Emby.Server.Implementations.Services.ServiceHandler.ProcessRequestAsync(HttpListenerHost httpHost, IRequest httpReq, HttpResponse httpRes, ILogger logger, CancellationToken cancellationToken)
   at Emby.Server.Implementations.HttpServer.HttpListenerHost.RequestHandler(IHttpRequest httpReq, String urlString, String host, String localPath, CancellationToken cancellationToken)