Can a virus infect different computers connected to the same router?

[Black Fire]

does depend on the virus if its merely a trojan then it might no replicate to other systems but there are some worms which search local networks before trying to infect other places, get your antivirus sofrware aswell as malware also firewall the hell outa the system if theres info going out which the firewall thinks is suspicious then it will kill it.....