There's little or no point in buying the router from the ISP, unless it's an unavoidable part of the contract and is included 'free'. It's so easy to set up a router that nobody need fear that it might be too hard. In most cases, all you will need to do is enter your ISP login name and password, and the rest is filled in automatically. In your case, being on a very long line, it would be well to choose the router with great care.