Adding new connectors means you only need about an inch extra on each side. Very low skill required if you have the (cheap) tools to do it. Actually putting new wires in place is a bit harder but still fairly easy. Attach some string to the old cable, pull it all the way through the walls. Attach the new cable to the string, then pull that through the walls. Then just add the connectors like the other scenario.
If the holes are sized for a single ethernet cable, you won’t be able to pull through two. If your confident holes are all oversized, sure go for it. Otherwise you risk getting it stuck half way through a wall and pulling the two cables apart
Adding new connectors means you only need about an inch extra on each side. Very low skill required if you have the (cheap) tools to do it. Actually putting new wires in place is a bit harder but still fairly easy. Attach some string to the old cable, pull it all the way through the walls. Attach the new cable to the string, then pull that through the walls. Then just add the connectors like the other scenario.
Pull the new cables taped to the old cables, no need for the string step.
If the holes are sized for a single ethernet cable, you won’t be able to pull through two. If your confident holes are all oversized, sure go for it. Otherwise you risk getting it stuck half way through a wall and pulling the two cables apart