jackfry: I'm not 100% sure tbh. It's really temperamental. I'm trying to get an upgrade on it and hopefully that will fix it.
If you're past your contract period, one way to get a new modem/router is to switch ISP. Or, to tell your existing ISP that you intend to switch ISP unless they match the package you're going to switch to, including provision of a new modem/router.