Sorry if this is rather basic, but I can't find the relevant information. I apologise for any misunderstandings in my question. What is puzzling me is how a router accesses the global internet.
At present, my internet is connected through an integrated router/modem (Technicolor TG579var) so it isn't obvious how it is configured. The ISP is Zen Internet and the actual provision is by OpenReach. I want to move to using a Draytek Vigor 167 as a simple VDSL modem, and a Mikrotik router to interface my systems to the modem.
A traceroute shows simple routing from the private LAN to the LAN gateway, and thence to one of my public IP addresses. But the next step is to the address that the Technicolor reports as the gateway. It is not in the same subnet as my IP addresses, nor even in the same IP space at the top level. How does the router know how to get to it?
Is information acquired by PPPoE? Or does DHCP need to be used on the WAN side? Even though I know what the IP addresses must be as they are fixed.
Clearly the Mikrotik router needs PPPoE client configured with the Zen credentials. But what other configuration is needed to make the WAN side work with the ISP, Zen?