It is a 3.0i. Just for anyone in the same situation I have the solution.

First, do not squeeze and pull. If you look at the connectors, there are two small slots on each connector. If you push into these slots with a small screwdriver, you can push out a u clamp (green in my case). Once the clamp is out, the connectors will slide right off the fuel filter.

In my case I managed to get the u clamp out intact, but it looks like a part which is easy to break, and one which you should probably replace with the filter to ensure a tight connection.

I have to say I would have been much more comfortable with a couple of clamps.