I am working on a guide to explain optimal Ethernet setup for grounding and shielding.  It is best to start at each computer and ensure they are grounded.  Ground the Ethernet cable at each computer as well.  Desktops already do this.  For laptops you may need an adapter which we carry.

Then as each shielded, grounded Ethernet run goes back to a metal switch or hub we like to isolate them.  I have gone into this a bit in another thread here:

I like routers and switches to be grounded one time through one port only.  I like the other ports to use isolators to avoid ground loops.  I like computers and their ethernet cables to be fully grounded AT the computer NOT having ground come from the switch.