First, do a complete reset of the router and set up your admin and wireless access passwords again. Failing that, check and make sure the firmware for the router is up to date. If it isn't, update to the latest version. If that doesn't solve it, see if a friend will lend you their router for a few hours. Hook up your computers to the friends router and try copying some data in the same fashion you were before via the mapped network share via both wired and wireless (try to borrow from a friend with a wireless router for more accurate results). Also check the physical cabling between the PC with the RAID array and the rest of the network.