I have just moved to a new apartment which has cat5e wires running through the walls to each room and to a centralized panel. I got a guy to crimp both ends of the wires and tested the network speed of the wires using a 1gb router. The computer I used to test (a 2017 macbook pro has a gigabit nic).
To my surprise, I only got the speed of 100MiB. I also tested a stock wire I had lying around and connected it directly to the router (got 1GB as expected).
Suspecting something is wrong with the wiring, I used a professional wiring testing tool to check the cable wiring which indicated all 8 wires are connected (see image)
I'm suspecting something is wrong with the wire, but it's brand new and tested well by the wiring check tool. Can you think of a reason for the speed to only get to 100MiB?