We recently renovated which included a new sleep out / office. Our Electrician installed two Ethernet sockets - one in the House (next to our Fibre ONT and wifi source) - the other in the outside room.

Since then we have not been able to use the outside Ethernet port at all. I am trying the following setup:

ONT --> Spark supplied wifi modem/router (blue WAN socket)
Yellow LAN port --> Ethernet wall socket 1
Ethernet socket 2 ---> device eg ps4, Apple TV, laptop.

Wifi works perfectly, as does LAN output when a device is connected directly to router.

I have opened the cover of both Ethernet sockets and also got under the house - there is definitely blue cable connected at either ends, and cable running under the house ( it does travel underground for about 1000mm but assume they used tubing for that).

I have read and watched a lot about patch panels or switches - are these required for just a single Ethernet line? Something with my Router set up? Or just wired incorrectly (perhaps there is a way to test the cable between two ports to ensure the circuit is not broken).

Any advice is appreciated.