If everything worked fine before you replaced the router, and now no longer works since changing the router, than your problem is most likely with the router. I'd try swapping back to the old one and see if things start working again before spending a whole bunch of time poking and prodding at settings.
Once you've verified the single source of failure, then you could start checking if it's (a) something in the router blocking the Amiga from connecting, or a setting that needs to be enabled, or (b) something on the Amiga that needs to be updated to allow it to "talk" to the new router. For example a DHCP setting or a static IP assign, etc.