I have two minis and a roamio Pro, MOCA on all three. The bedroom mini (new) worked fine but the basement mini stopped working telling me the connection was not fast enough to support playing (V69 I think). The MOCA settings all looked fine and the basement mini could get the now playing list and connect to the internet OK.
So I switched minis and the basement still had problems. I went to another cable connection and it failed too. The bedroom ( with switched mini) still worked fine.
On a whim, I remembered I had a network cable connected to the roameo going to an Ethernet switch. I disconnected that cable and all the minis now worked fine on all the connections.
So somehow, with the roameo set for MOCA and Ethernet, it got confused supporting the minis over MOCA.