🚫 no idea why the USB -> Fiber lost connection

[Lord of nothing]

Hi
I got that: https://www.icronshop.com/fibre-usb-extenders/icron-raven-3124 a while ago. At first the run 24/7 perfectly. When it got colder the beginn to lost the connection. The local box is in my office room who is well temperate. The Remote Box was under the attic and now in an room on the attic who is a little bit headed.
The problem with that box is the connection get loose after I replugged in the power socket. That mean: the run for ~30Min -> 1sec connection lost -> 10min later -> lost again for 1sec,... so on until the lost the connection totally. 
I have no clue what that could be! I run 3x Delink Media Converter who are next to the Box. Broken Cable? So there is no reason why it "fade out". 
Ideas?