I have ordered an Asus RT-N16 router. Could someone please tell me which ADSL2+ modem I should buy for best compatibility with Tomato USB.
Usually, you can't buy standalone ADSL2+ modem, you have to buy a "router" and only use the modem section by placing it into "Bridge" mode. You really only need 1 LAN port but usually you get 4. There are many makes on the market, some chipsets work slightly better than others. The routers usually provided by the ISP's usually have crap router software, but since you don't use the router section anyway, they are fine for Bridge mode.