I have an RNX-N300X wireless card. The card will connect to both the router and the Internet but if i use about 10MB the internet will stop working. The card remains connected to the router though. To fix it I have to reconnect to the router and it'll let me use another 10MB or so. I remember i did not have any problems on previous versions of ubuntu just on this latest one. I also have the same problem on the latest Mint version but not the previous.