I am unable to connect to Wifi when I am upstairs due to my router being in the basement. Can I (leagally/freely) connect an older router I have to an ethernet port on the top floor of my house and use that router as its own wifi network? (i.e. Router A is in the basement, Router B is on the top floor of my house. Router B is connected to an ethernet cable that is connected to Router A. Router B now has its own WiFi network.

Is this possible? and (somewhat more importantly) is this legal and could I possibly be charged by my provider for this?

(Sorry, I am a younger IT Kid doing this for a friend and just trying to make sure that there aren't any negative implications.)

  • You could just use the old router as an extender. You can easily Google how to do that. – MC10 Jul 27 '15 at 18:09
  • Yes; What you want is possible. We cannot speak of the legality of it though. – Ramhound Jul 27 '15 at 18:14
  • Generally though- would this be something that an ISP would charge for? (I know it is almost an opinion question but I would really appreciate a confirmation from someone who knows a great deal more than I) – Ghost Koi Jul 27 '15 at 18:17
  • In theory, no, it doesn't make any sense to charge for this – especially if the ISP's own gateway already has a Wi-Fi network. (In practice, ???) – grawity Jul 27 '15 at 18:38

It's usually possible, depending on the router, is almost certainly legal (anywhere WiFi is normally legal), and I've never seen a provider charge extra for it, if they even notice.

You may have to do some fiddling with router B to get it into what's usually called "Access Point" mode.

  • I just connected the router b to the Ethernet port and (after a few minutes of diagnostics) the second Wifi network is up and running. I am just a little skeptical of it though, Is it generally this easy? – Ghost Koi Jul 27 '15 at 18:10
  • @GhostKoi : Sometimes! Sometimes you have to make router B stop trying to set up NAT within the other router's NAT and sometimes the routers both try to issue IP addresses to machines, so you usually have to turn off some bits of the router B-equivalent (which is what "Access Point" mode usually does). – Aesin Jul 27 '15 at 18:13
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    Usually you would better not use the WAN port of router B to connect it on router A, but instead use a LAN port. This implies it's a real router and not a box (modem+router) which then does not have a dedicated WAN port so you would use LAN port by default. And disable DHCP, UPnP and similar things on router B so all the network is managed by router A. (router B only acts as a switch and WiFi access point) – piernov Jul 27 '15 at 18:27

Sure, it's possible. Most providers only care about things like sharing said network with all your neighbours.

(Even then, "forbidden by ToS" still doesn't mean "forbidden by law".)

Perhaps, using nonstandard radio frequencies for Wi-Fi would be illegal, but your routers won't let you do that anyway, so that's not a problem.

As for technical side, this has been asked and answered many times on the site (thus the -1)…

  • One way would be to just connect B's "WAN" port to A, like you describe – basically to stack the two routers, with their own networks.

    However it's a messy way of doing it, especially if you ever needed to configure port forwarding. One layer of "private addresses" is already awful enough; it is best to avoid such stacking as much as possible.

    So don't do that.

  • Instead, consider what the "router B" consists of. Usually it's a "home gateway" containing an Ethernet switch, a Wi-Fi access point, maybe an ADSL modem, and only then a router – all in a single box.

                                               ┌─ ["LAN" Ethernet ports]
    ["WAN" Eth port] ─── [NAT] & [IP router] ──┤
                                               └─ ["LAN" Wi-Fi access point]

    Out of all these parts, you only need the Wi-Fi access point – as in the name, the AP's job is just to provide Wi-Fi access to a LAN, exactly the same way an Ethernet port provides access to a LAN, and since you can have multiple Ethernet ports, you can also have multiple Wi-Fi APs.

    So ideally you would have only one network, with "router A" doing the routing, but multiple access points connected to it, all with the same SSID (network name).

  • To do that, you have to disable all 'router' features in router B. That's the "access point" mode which Aesin mentions.

    Many gateways don't actually have such a mode, though, so you might need to configure it manually:

    1. Most importantly, turn off "DHCP server" in router B.

    2. Change router B's own IP address to be in the same network as router A. For example, if A currently has, then configure B to be or similar.

    3. Change router B's Wi-Fi settings to be identical to router A's – same network name, same WPA passphrase.

    4. Finally connect both routers using their LAN ports.

    (Step 4 could be "switch router B's WAN port to bridge mode", but too many gateways don't actually have an option to do that either, so just using the LAN ports is practically the same thing.)

The instructions are a bit vague because different routers & gateways vary a lot in what features they support, in what those features are called, and in how they're configured.

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