QuiGoneGin

i used the ookla and quickline speedtests. The fibreoptic cable goes into some sort of box on the first floor, and from there we have 4 cables going into the wall to 4 spots on 2 floors. I tried to switch the cables from the box to see if one is broken but this doesnt work. the cables on the first floor output gigabit but on the second they dont. It could be that the guy who installed the cables broke them somehow when routing them upstairs...

Not a broken cable, i tried 3 different ones all have the same result.

My family recently got an upgrade from 100mbit to Gigabit ethernet and with it the service provider routed fibreoptic cables. If i hook up my laptop into the wall with a Cat 5lan cable on the first floor, it reads around 500mbit/s Up and 950mbit/s down. If i plug my laptop in on the second floor it reads 90Mbit/s Up and down. My Gaming PC(Ryzen z 1700X, X370killer sli MOBO) also only reads 100mbit/s while our 7 Year old iMac on the first floor reads 750Mbit/s Up and 800Mbit/s down. Is it a software issue or purely hardware? I tried changing the Network speed from automatic to 1GBit but then the LAN won't connect anymore. Any tips on solving this? (on other forums they only talk about the cable and the Bandwith limit of the router or computer but that doesnt seem to be the problem) Thanks for the help in advance...