TLK105: reference ground of layout MAC interface

Hi team,

When a high power LM25145 DC-DC  works beyond 20W, the Ethernet communication is interrupted. When supplying this 20W with an external LM25145 board, the Ethernet communication is fine. I saw this customer directly uses power ground of high power LM25145 DC-DC (up to 60W) as reference ground plane for MAC interface. I measured the switching noise on these single-ended I/O pins are up to +-800mV as below shows. I think it might be the root cause. I think this kind of switching noise impacts the single-ended MII/RMII interface, but impact nothing of the MDI differential interface. However, I didn't see we have MAC interface layout guideline in our datasheets.

Thanks.