Configuration adsl modem and connect to switch for internet distribution

I have an adsl modem and a d-link switch (8 port). I have made a lan and configured the adsl modem with dhcp. the connetion is working well on one computer in the room where the modem and switch are. when i go into the nest room with the same laptop, it is showing a but i can browse. it is taking so long until it times out. Can the distance have an effect? How can i successfuly have all the computers connected and working? I have checked all the settings but couldn’t figure why i can not connect to the browse the internet when i go to the other rooms. Even with all the cables unpluged as long as it is in the other rooms other than where the modem is iam failing. Please help.