Except WE DO NOT EVEN HAVE A FUCKING CISCO ROUTER. They repeatedly insisted that we did. We do not.
And they will not do anything.
They're insisting it's our fault and they've never done anything like this (even though they have twice before and fixed it on their end both times) and they have no records of anything like this happening before.
They also simultaneously insisted that we were self-generating IPv6 addresses (but I guess only when talking to their servers? Sure, that makes sense) and that our gateway is set up not to pass IPv6 traffic, even though their servers are seeing us as IPv6.
And he refused to let me talk to anyone else.
I guess we need to find a new upstream IP provider, because I have no idea what to do next.
Also, I was pretty pissed off that despite the fact that I've been the one doing all this calling since always that I had somebody who comes in and does our networking work.