A Mini (any) is sensitive to IP changes. I would power off the Mini, Roamio and router. Then power up the router. When it's done, power up the Roamio. When it's up and can see the internet, power up the Mini. When it's up, test it.
The Mini with a wifi 5 adapter only talks to the router and should not have coax or Ethernet connections.
The Mini with a wifi 5 adapter only talks to the router and should not have coax or Ethernet connections.