If you changed from a 40/2 to a 40/10 Openreach product then DLM is automatically reset.
As G.INP was active previously it is highly likely it will re-activate in 2-3 days and restore your previous downstream stats.
There is nothing you can do to influence this except leave well alone. Do not start doing re-syncs or power cycles.
If you already have done, it may take a bit longer for DLM to reactivate as you may have made it think there is more instability than there is.
Incidentally FTTC DLM operates at cabinet level, which is where the DSLAM is, not at exchange level.
Kindness isn't going to cure the world of all its awfulness but it's a good place to begin. Daisy Ridley.
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