In the UK at least, most of the bigger ISP's will supply a wireless-capable router free when you sign up for their service..and happily supply instructions on how to connect multiple hosts, enable sharing between them.
The argument that you run a service from your home network? isn't always the case either..my DDNS exists purely to allow me to connect *into* my home network to control my PVR etc. and ok that's me, but I'm fairly sure that's the case for many others.
Using BitTorrent? They don't mind...if they did, why would they not just cap download quantities across the board? They don't, but you may pay more for uncapped services..
Having these issues? Change your ISP..
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