I use Miami Dx with ADSL now. But Miami v3 works fine too,
I have both.
Make sure you have the right driver selected for Sana I use the mni drivers that come with MiamiDX (they will also work with Miami v3) on my real Amiga. With Amithlon you have to use the powern2k.device.
In the settings make sure that it is set to DHCP and that use DHCP is active in prefs
But as suggested before use Miami Init for both Miami and MiamiDX. load the settings in and it should work.
Also find out if your ISP uses ppoe as this will make a difference.
If you got to
www.nodicglobal.com Holger has a very good tutorial in ADSL/Cable setup.