If DLM has enabled interleaving that is because of the error rates on your line.
Yes it adds 8ms to latency, or more if things are really bad, but without it the error packets all have to be re-transmitted.
I'm not a gamer, but from what I've read in the past that is worse than having the interleaving overhead.
Have you checked the error rates, and investigated whether or not you can reduce them. Either by changes to equipment or its location, or by reducing the connection speed which AIUI is not as important as latency for gaming. Reducing the speed reduces errors, and if you do that then DLM may relent after a while and restore Fast Path.
Router stats including the error statistics as well as the basic sync/attenuation/noise margin and interleaving values would be useful.
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