hi there sorry if this is on here already. i have a few f5s 4 in total 2 are fine 2 doesnt connect to internet through wi fi dongle supplied by the seller. i ve swapped dongles about with one i know work so i m assuming it s a fault with the box and they also connect no problem with ethernet cable which is fine for one of them. the last one i bought makes a large buzzing sound when powered up can i fix this or is the box knackered.