I've thought about it a lot, and this seems like it's the best way to go. I've tried everything to the point that I'm fairly certain the problem isn't on my end. That leaves Bungie's networking and the ISP itself. But our ISP has tried to fix it twice and couldn't find any problems; Bungie knows what their game needs better than anybody, maybe they could issue a general statement of what the game requires forwarded/opened/etc that we could individually get to our ISP in hopes of them finding the problems and fixing them. Or, like OP said, maybe our ISP is just full of blithering idiots. It wouldn't be the first problem we've had with them...