Replacing your ISP router | MikroTik Configurator

Most people arrive here with exactly one box in the house: the router the ISP sent along. That box does everything at once: modem, router, firewall, Wi-Fi, DHCP, and with some providers television and telephony as well. The moment you put a MikroTik in front of it, those jobs come apart. This chapter is about the preparation, not the buttons; the buttons are in Example: replacing the ISP router.

What you gain and what you lose

You gain a router you can see all of: a firewall you read yourself, VLANs, VPN, DNS with a cache, static routes, and a configuration that is text and can therefore be kept, compared and repeated.

You lose the things the provider did for you. When there is an outage, their router is the one they can read out; yours is not. Firmware no longer arrives by itself. And the app you used to look up the Wi-Fi password does not talk to a MikroTik. That is a fair trade, but it is a trade.

Write this down before you start

Do it while the old router still works. After the reset it is gone.

How the internet arrives. DHCP (cable, or a modem in bridge) or PPPoE with a username and password. On fibre there is often a VLAN number with it, for example 6 at KPN.
The VLAN number for internet, and for TV if you have it. Those differ per provider and sometimes per region.
Your LAN range. Usually 192.168.1.0/24 or 192.168.0.0/24. Keep it and nothing in the house has to be changed.
Fixed addresses (DHCP reservations). MAC address, IP and what the thing is: printer, NAS, cameras, home automation, a thermostat.
Port forwards. External port, protocol, internal address, internal port. Write down what each one is for as well; half of them are usually stale.
Wi-Fi names and passwords, for the normal network and for the guest network.
Devices with a manually configured IP. They are not in the DHCP list and you only notice them when they break.
IPv6: whether you get a prefix from your provider, and how large.

For an idea of what such a list looks like when it is written out properly, see Example: office with VLANs.

Bridge mode on the modem or ONT

A MikroTik router has no DSL or cable modem of its own. Whatever your provider delivered stays necessary as the access device, but it has to stop being a router.

Fibre with a separate ONT. That is already a bridge. Cable from the ONT into ether1 and you are done. Do ask which VLAN to use.
Cable. Put the modem in bridge mode, usually through the customer portal or the helpdesk. Some modems remember the MAC address of the router that connected first; then clone MAC address on the uplink helps, or leaving the modem unpowered for half an hour.
DSL. You need a modem that can bridge. If the provider's box cannot, it stays the router and you are stuck with double NAT.

Double NAT is the classic trap: everything appears to work until you want to forward a port or run a VPN, and then nothing works. Put the modem in bridge, or accept on purpose that those two things will not happen.

Television and telephony

This is why the provider's box usually stays in the meter cupboard after the switch.

Television runs over multicast at many providers, sometimes on a VLAN of its own. The configurator handles that: switch IPTV on in the internet settings and it creates an IGMP proxy and lets multicast from the provider through the firewall. If it stays stubborn, leaving the provider box on its own port with its own VLAN is often the quieter answer. See Recipe: IPTV.

Telephony you cannot take over. The phone socket sits physically in the provider's router, and you usually do not get the SIP credentials. Leave the handset on that box and give the box a defined place in your network, or move to VoIP you run yourself. See Recipe: VoIP.

Switching over with the least downtime

Finish your configuration in the tool while the old network is still running. Pick One device, your model and the role Home router.
Keep your old LAN range, and keep your old Wi-Fi name and password too. Then nothing in the house has to notice anything.
Enter your fixed addresses as static leases and your forwards in the Port forwards list.
Reset the MikroTik and paste the script while it is connected to nothing but your laptop. See Using the script.
Only then put the modem in bridge and move the cables. That is the moment you are offline, and it lasts minutes instead of an evening.
Keep the old router until a week has gone well. It is your way back.

What the tool cannot do

The configurator only reads a RouterOS /export. It cannot read the settings of an ISP router, whatever brand of box your provider shipped: those are closed file formats. So you build your configuration from the list above. That is less work than it sounds, because the wizard asks for exactly those things.