Laptop only gets 100 Mbps on a 250 Mbps plan

Is it on wifi or cable? Exactly 100 is suspicious. On cable it usually means the link is running at 100 Mbps instead of gigabit. Bad or old cable, or a dodgy port. Check the adapter's link speed in network settings; if it says 100 Mbps, swap the cable first. On wifi, you're probably on 2.4 GHz. Move to the 5 GHz network if the router has one and test again close to it.