Hello @daniel4579329 ,
try to use speed auto the switch should be able to autodetect the speed of the other device.
You need also a straight cable not crossover between a router interface and a switch interface.
Hope to help
Some gig interfaces can negotiate and use lower speeds. And some gig interfaces just do gig and not slower. We need more information about the switch and the switch interface so that we might know whether negotiation was possible.