Problem solved, I powered off the wireless router, back to my old safe and fast wired LAN.
Have one more question regarding this LAN: In my LAN I have my PC and a NAS, both with a static (fixed) IP. How can I block the PC from accessing the NAS? I tried the router's firewall but I see no option to do so. The reason I'm asking this is because sometimes I have guests at home that connect to my wired LAN and I would like to block those guests from accessing my NAS without having to set the firewall in their computers. Is there a LAN traffic management software that will enable this?