We have internet in our office from 2 different sources. One is a little satellite dish, the other is a microwave radio pointing back towards a ISP downtown. Neither of which are very reliable. But, usually and fortunately, when one is out the other is up. Is it possible to plug one ISP into the NIC and set the other up with WIFI. Will they fail over to the other when one or the other fails?
you will probably be charged double, where as you may be charged extra anyway. An easier solution (although it slows down the connection a little) is to buy a router and run the connection up to the upstairs. This will also probably be cheaper and easier to do with a wireless router.
I'm shooting off the hip here, but maybe this idea will lead to a solution. I'm assuming you have two standard home routers and each is hooked up to it's own ISP uplink. 1. On both connections, disable DHCP, turn on static IP assignments. 2. Connect both to the same wired LAN using an intermediary switch. Plug your computer into the LAN. Forget wifi for now. 3. Use a batch file to attempt to ping something like Google. 4. If the ping is unsuccessful, the batch file uses netsh to set the static IP to the other gateway/IP scheme. 5. Loop your batch file. I'd probably add a 60 second pause so it wasn't constantly doing it. Haven't personally tried it, but that's the way I'd attack it.
here's an alternative option... and I do this at work, for our networks.. 1) Set up both connections into one router. 2) Make sure you have an appropriate router. (Dreytek for a small office is ok). 3) Set them both up as inbound connections, and use one as your primary, and then the other as a secondary. 4) You can configure your router so that as soon as the primary fails the secondary kicks in. 5) This should be an effective solution, unless both fail at the same time. Give it a go. I've found that our internet is always up and running as a result.
You might want to just look at a router that has dual WAN ports (two upstream Internet connections)... probably the easiest thing to do since that's what they are made to do (if one is down, you still have connectivity). For example: http://www.amazon.com/Cisco-Business-Router-Internet-Affordable/dp/B005UWCTJS