Yes I thought it was a bit funny, but its their ISP and thay call the shots. "blueyonder.co.uk"
Each NIC I have installed has its own unique MAC address, blueyonder requires that MAC address before I can connect "we are talking about a DSL here", when I first connected a engineer came round and installed some cheap £12.00 NIC card, blueyonder charged me £75.00 for it, but you live and learn. The following day I replaced the card with a netgear. When the new card was installed, I could not connect to the net. I phoned blueyonder who explaned thay would need the mac address of the card before thay could connect me, so I pinged the card got the mac address gave it to them over the phone and behold I was connected. Its not a restriction in one way, as at any time I can connect to the selfcare section of the site and choose which of the two MAC addresses to use ( its now three MAC addresses I have registered ). but it is a restriction as I can only use one MAC address at a time, which ensures I only have one computer connected at any time. Hence the need for a router, to connect all three computers. Looking at it from another point of view, only the Mac addresses I have registered can use my connection to connect, this prevents abuse by dodgy engineers whom will splice into someones cable for £50.00, allowing unwelcome persons free access to www at my expence. Remember DSL is basicly just a lan connection, I dont understand it all but it works. I hope this clears up the misunderstading.