the port forward is referring to the NAT ip addresses, not the external ip your ISP is giving you: so if all your machines are getting 192.168.1.50-100 from dhcp, switch one of them to a static ip ...
One type of electronic device to especially avoid is the microwave, which emits a strong signal in the 2.4GHz band, the same wireless band your router operates in. Be careful not to stick your router ...