The second network name, and why it exists

Every access point announces itself with a network name. The router has one; the extender, being an access point too, must have one as well. A maker can give the extender a distinct name, typically the router’s name with a suffix, or can let the extender copy the router’s name and key exactly. The first arrangement makes the two signals visible and separately selectable. The second makes them look like one network and leaves each device to move between them on its own judgment.

A network name, the SSID, is a label carried in the beacons an access point sends several times a second. It is not unique and it is not an address; it is what a device shows a person so they can pick a network. Two access points may use the same label, and a device will treat them as two doors into the same network provided the security settings match.

Each access point also has a hardware address, the BSSID, which is unique. When a device joins a network it joins one specific access point by hardware address, however the name is shown. A household with a router and an extender therefore always has two doors, whatever the labels say. The label decides only whether a person can see that.

Extenders that create a distinct name usually build it from the router’s name. The convention varies by maker, but the shapes are recognisable.

The advantage of a distinct name is control. A person standing beside the extender can choose its door explicitly, and can tell at a glance which door a device is using. The disadvantage is that devices do not move between differently named networks by themselves. A phone that joined the router downstairs stays on the router until that signal fails outright, even when it is sitting next to the extender.

Units that copy the router’s name and key remove the second entry from every device’s list. The household sees one network. Underneath, nothing has merged: there are still two access points with two hardware addresses, and a device is attached to one or the other at any moment.

What changes is that devices may now move between the two doors without anyone choosing, because they regard them as the same network. Whether they do so promptly is another matter, and it is decided by the device, not by the extender. How a device decides which signal to use explains why a phone can sit beside the extender and stay stubbornly attached to the router.

Under the one-name arrangement, the network name no longer says which door a device is using. What does say is the hardware address of the access point, which most phones and computers show in the detailed view of the current connection, and the signal strength reading, which is strong beside the door in use and weaker beside the other. The extender’s own configuration page lists the devices attached to it, and a device absent from that list is attached to the router.

Some makers’ applications show the same thing as a map of which device hangs off which unit. That is a presentation of the attachment table, and it is the extender reporting its own view rather than anything measured at the phone.

Dual-band equipment can publish the 2.4 GHz and 5 GHz bands under separate names or under one. Separate names let a person pick a band; a single name lets the device pick, and lets the access point steer it. Extenders inherit whichever convention the household router already uses, with their suffix appended if they use one.

A device that has only a 2.4 GHz radio sees only the 2.4 GHz entries, which is why a list of networks can differ from one device to the next in the same room. That is the device’s radio, not the extender, deciding what is visible.