I am assuming your new desktop is receiving a wireless signal. The problem is your router. The router can handle a limited number of devices. Sometimes tablets and computers will use more than one of these ports, because the router thinks they are different devices than earlier. The hardwired one never confuses the router, since it has only one constant path. Your choices would include getting a router that has a larger number of user pathways, hardwiring your new desktop, or continuing to power cycle the router.