My brother recently created a Minecraft Nitrado server to play with his friends there. Whenever he takes the server online I have the feeling that my internet speed is very negatively affected. (videos etc are delayed and websites take a long time to load) my question is whether this server can have a negative impact on my connection or whether I'm just imagining it.
Your brother, like his friends, join on an external server. Of course, if you are on the same network, then you share the line.
No it didn't. The servers are in the data center and not with you.
Of course but then it shouldn't be any different than if he plays another online game right?
Right, it won't be any different. Unless he is downloading something or streaming. The more he uses, the less performance is logically available in the rest of the network.