offtopic - RJ45 switch

["Jon Macmichael" <jonmac@xxxxxxxxxxx>]

Have switched from a 'USB - Ethernet adaptor'  to a Ethernet PCI card.

This setup has bypassed my 'legacy - pull the plug out of the adaptor to
physically disconnect from the internet'.

Bought a second RJ45 cable (blue male/male patch cable) and a RJ45 telephone
joiner to join both cables together. This should have provided my physical
disconnection to the internet, but it just doesn't work.

Any help re: what cable is necessary, or where to look for a single RJ45
cable with a physical switch in the middle, appreciated. (too awkward
reaching round the back of the computer)

Thanks
Jon