How do I set up a new router?

Connect it to the line, change the two things that come preset — the administrator password and the network name and key — then decide how it will coexist with whatever box the provider supplied. That last decision causes most of the later trouble.

Most of a setup is done for you. The parts that are not are the parts worth doing carefully.

Before anything is plugged in

Note what the line needs. Some connections require credentials, some require a particular identifier on the line, and some just work when the cable is connected. The provider publishes what theirs needs, and having it to hand turns a frustrating evening into ten minutes.

Note the model of the provider’s existing box too, because the coexistence question below depends on what it can be told to do.

The two things to change immediately

The administrator password. Preset credentials are the first thing anything hostile tries, and on a device that faces the outside world that matters more than on anything else in the house.

The network name and key. A default network name often identifies the maker and the model, which is more information than a stranger needs. Choose a name of your own and a long key.

Everything else can wait; these two cannot.

The coexistence decision

This is the part that produces trouble months later. If the provider’s box is routing and your new router is also routing, there are two layers of address translation between the house and the outside, and things that need to be reachable from outside become awkward.

Three ordinary arrangements, and the provider’s own documentation decides which are available.

Bridge or modem mode on the provider’s box, so it terminates the line and does nothing else while your router routes. The cleanest arrangement where it is offered.

Your router as an access point only, with the provider’s box continuing to route. Simple, and it means the provider’s box governs the network.

Two layers, deliberately, with anything that needs to be reachable configured on both. Workable, and the one to choose knowingly rather than by accident.

The settings worth visiting once

Firmware. Check for an update on the first day and turn on whatever automatic arrangement the maker offers.

Wireless bands. One network name across 2.4 and 5 GHz is the sensible default, so devices choose for themselves. Keep a separate 2.4 GHz name in reserve for equipment that insists on one.

Address handing. Note the range the router hands out, because anything you later want at a fixed address has to sit where it will not collide.

Guest network, if visitors or smart-home devices are going to be on it.

Time zone, which sounds trivial and is what makes the logs readable later.

Then confirm it works before tidying up

Check a wired device and a wireless one. Check a device on each band. Walk to the far corners with a phone. And write the administrator password somewhere that is not a note stuck to the router, because the next time it is needed will be a day when nothing else is going well.