there shouldn't be any problem if your brother used to browse the net when you are playing , because it needs a very very limited portion of your total speed , like if you play for one hour then at max ~~ 20mb traffic will be exchanged ,
technically you should have problem playing game while your brother uses internet for browsing ,on the other hand if your brother tries to download something then you will again have problem in playing and your pings will fluctuate because a major portion of your bandwidth will be consumed in downloading , i will advise you to check the connections on SWITCH and if this is a ROUTER then let me know back again , or try to setup a network through operating system but i do not recommend this ,