Splitting signal with cat5 splitter to 2 TVs

[Human 19]

I have already connected the computer upstairs to the VU+ duo 2 downstairs, for streaming, via a cat5 cable from the ethernet port.
I have also recently set up a raspberry pi 2B with Kodi and can stream from the box also. I want to put this pi2B in the kitchen.
I bought a cat5 splitter to be inserted into the ethernet port of the VU+ , and plan to run the 2nd cable to the kitchen.
Unfortunately, I can only connect to either device from 1 particular side of the splitter.

This is regardless of whether I have 1 or both devices connected at the same time. Even with my normal PC connection, if I move the cable to the other outlet of the splittter, it no longer connects.

Is this a problem with the splitter or something to do with the VU+?
Thanks

EDIT: I should have posted this in the VU+ Duo2 thread. Hopefully it is still relevant here**