Sorry, used the wrong term. By WAN I meant the broadband telephone line. Modem cards for dial up connections were common back in the day, but since ADSL and beyond I don't recall any commonly available products, USB winmodems aside. VDSL/Fiber capable cards would be very handy to build 100% FOSS broadband routers, but they seem next to unobtanium.
Comments
That's because there is no single "WAN interface". The WAN port on the router is often just a differently labelled Ethernet port.
Sorry, used the wrong term. By WAN I meant the broadband telephone line. Modem cards for dial up connections were common back in the day, but since ADSL and beyond I don't recall any commonly available products, USB winmodems aside. VDSL/Fiber capable cards would be very handy to build 100% FOSS broadband routers, but they seem next to unobtanium.