I use a modem ahead of of the MX that handles the ADSL/VDSL/PPPoE issues. There are plenty of modems that do a good job. Depending on your location, there is probably a specific modem that handle the idiosycracies of the local ISPs, which simplifies matters. If you need dual ADSL lines, you have options -
Use the principal designated "Internet" port on the MX together with the alternative WAN port.
Use a modem/router in pass-through mode that has the ability to connect to multiple WAN/ISPs concurrently (these often have LTE failover capability built in)
A question i need configure 1 router with 1 port ADSL. If I consider some model MX i will be coverage ?
Originally I had an MX64 that was connected to the ISP's termination via a modem (Vigor 130 UK model). This was a PPPoE connection.
For security reasons and the need to have an IGMP Proxy configured, the MX64 uplinks to a 3rd party security device with 2 LAN ports, one for the MX64 and the other for the multicast networks, IoT, Chromecast etc. The third party security device's WAN port is connected to the original Vigor 130 modem.
Note: confusingly there is both a modem and a router named Vigor 130. The router is sold in the US, the modem in UK and Europe. Do not assume they are interchangable.