Hi,
Noise can come from everything and everywhere...
Have you tracked down your problem ?
Plug and unplug one cable after the other and at each end at a time...
I've had strange behaviors with shielded Ethernet cables (FTP or STP) producing more noise than unshielded (UTP)...
You have to test, find the cause and find a solution..
Each case is different.
Good luck,
73 Patrick TK5EP