When I had a DLM reset G.inp was removed but came back on a couple of days later on downstream, before that I had G.inp on upstream but only briefly when there was fault on the line. Your speed seems to be much improved now so just see how it goes over the next few days. I don't suppose the engineer offered any explanation for why your speed was hit so hard by DLM just after vectoring was enabled. Thunderstorms are supposed to be treated as wide area events and not cause DLM action, but who knows how BT's systems work!