I'm slightly puzzled as to what caused the DLM to put me onto an interleaved line, unless it really doesn't like CRC error bursts at all. The CRC spike is also confusing as nothing has changed in my setup for a long time, I can confirm that nearby thunderstorms do cause errors but nothing as bad as what I saw on the 20th.
As far as I can see everything is fine now looking at MDWS (apart from the interleaving), so is it just waiting for DLM to decide that interleaving isn't needed anymore?