Beijer Electronics iX T12C EN - Manual (Page 27)

Additional Installation Tips
A good solution may be to use a shielded Ethernet cable, but to connect the shield
at one end only.
One option is to break the shield, see 3 in drawing above.
A more elegant method is to expand the shielded Ethernet cabling with a piece of
unshielded Ethernet cable, see 4 in drawing above.
The shield can be grounded via an external 0.1 μF/250 V plastic capacitor, see 5 in
drawing above. This will connect the HF transients to ground.
Beijer Electronics, MAEN082D 27