yasamoka wroteThat's a router. So all he has to do is to open the router config and disable DHCP. Then he can connect the router to the modem (LAN port on router + LAN port on modem) without any problems.
If he knows the password to the modem, then further configuration can take place. But for now this should be alright, I guess.
Brilliant, thanks a lot. It worked :D