non gigabit ethernet?

[conscriptspider]

i have a gaming pc with a gigabit ethernet adapter using a cat5e cable and connected to my xb6 router with internet 600 and my down is just below 100 mbps and upload is around 20
so why is it not faster? wifi is 350 down and 25 up (with higher latency)

cat5e supports gigabit so does my board and the router so whats wrong?

also side bit why cant i change/find my dns settings?!?!?

[#2]

My first thought is that your computer is set to force a 100 mbps link speed.

Second thought..  Your Cat 5e cable, does it have all 4 pairs?  Or just two pairs of wires inside it?  Otherwise, swap the cable and see if that helps.