enable moca on xb8 ?

My xb8 admin page shows a red X by MOCA.  I have the XB8 in bridge mode with TP-Link Deco's acting as router/wifi.

The distant Deco is hooked through a MOCA adapter, but I don't think that is working as wired - it is working via wireless.

I have no MOCA adapter at the XB8, because I was told it has internal MOCA capabilities - altho it doesn't seem to be enabled.

The main ISP line has a MOCA-compatible splitter - one leg to XB8, the other leg to the distant room/MOCA adapter.

In the XB8 admin pages, the MOCA set-up page is grayed out.

How do I enable the MOCA properties ?