Error on 2 outgoing ports

I just pruchased a 16 port switch replacing 3 small switches. Everything worked before, but now I experience malfunction on several ports. Testing of the cables shows

15: open cable 11

9:  short 21 

I cannot find what this means.

If I plug these connectors directly in the router everything works fine.

What could be wrong?

Thanks for your help

Cheers,

Hans