Question about Delock HDMI Audio 5.1 Extractor, 4K, 60Hz

I have received a new Sunries IP TV box. Sunrise has omitted the Toslink from the box. The Toslink output of the TV only delivers stereo. Can the adapter deliver 5.1 via Toslink or does it only deliver stereo? With the Swisscom box, 5.1 came directly via Toslink, but via TV only stereo...