Is it a filtered master socket? Can you post a pic. You only need pins 2&5 disconnect 3
If you are trying to move hub to different location you could just leave filter in master and run a longer rj11 modem cable form filter to hub. If you want to use extension socket then connecting to pins 2&5 in master then connecting to pins 2&5 in extension and then use a filter to connect modem cable to hub. This may cause a reduction in your connection speed whereas first suggestion will not
modem cable rj11 like this.
No just it is not required and can cause interference. As long as you have the same colour connected to the same terminals and then use a filter at extension
If you are connecting to terminals 2&5 on the back of the detachable front plate of master and then connecting same coloured wire to terminals 2&5 in extension socket and you use a filter it should work