The three possible scenarios you seem to be facing are hardware failure on your existing router, channel crowding, or some sort of incompatibility between your device and routers. The quickest and easiest way to confirm which one of these it is, is by setting up a stand-alone access point right next to your router with a different SSID and try connecting to it.
If your device connects, it is definitely not channel crowding, and could be hardware failure on your existing router or some sort of incompatibility.
If your device doesn't connect, it's definitely not hardware failure on your existing router and could be channel crowding or some sort of incompatibility caused by something software related on your device.
Either way, it will start to help you narrow things down before you invest in a whole new setup which may or may not solve the issue.
