Today I have a 50/125µ LSZH Duplex Multimode fibre and still get the same results. So again my question: does anyone have an idea what I am doing wrong and how I could get these devices communicate...

Sorry, I just realized that I am using a single mode cable. :-( I will get a multi mode cable and try again.

Hello, I try to use a TP-Link MC200CM(UN) Gigabit Multi-Mode Media Converter (V4.0) together with an Aruba Instant On 1930 Switch. Therefore I have tested several SFP-Modules that are listed to be...