If you set a static local IP address for your Amiga on the router, you will probally have to get some DNS addresses. I had to do that for the static local IP address for both Miami and Genesis. (This was done for ease of use as I add to my local network. It helps me remember the address for whatever system is hooked up rather then letting my system possibly getting a different address then I remeber it usually being.)
In my setup, I gave my Amiga the local address of 192.168.0.2
My Gateway (the router) has the local address of 192.168.0.1 (This could be changed, but it was the default for my DSL modem/Router)
The netmask as 255.255.255.0
There's a good chance that these are gonna work on your system. Where you need help is getting the DNS servers for this particuar setup. These change from provider to provider. Call them up and tell them you need the DNS addresses so you can set up your PlayStation2 or your Gamecube. This avoids the "We don't support Amiga." comments from your ISP.
In Miami, the IP address, Gateway, and netmask are under the Interface->SANA-II Configuration.
DNS servers are set under Database->DNS Servers
Under Interface menu on Miami, make sure you have the proper type and driver setup as well.
Another thing to keep in mind is that the unregistered Miami has a time limit, and that registering Miami seems to be impossible right now. If I'm wrong, I hope someone lets me know so I can let our user's know.
This setup is working fine for my system. I have an A4000 with an X-Surf II card. I don't know how well it will work for different setups.