Connecting to my VM set-top box

[plumcloth]

I recently set usp my old RBR40, and all is working well. 

I was using powerline adaptors to connect from orbi to my Virgin Media set-top box, again all working well.

Then I replaced the powerline adaptors with an ethernet cable from the (modem mode) VM router to my VM set-top box - and the set-top box could not access the internet.

When I run the ethernet cable from orbi to the set-top box it works, but not from the (modem mode) VM router.

I have a NAS connected to my (modem mode) VM router, and this works fine, so I assumed the set-top box would too.

Can anybody help me understand why it doesn't work.

Thanks in advance, Pete.

[plumcloth]

Think I've answered my own question here - I think it must be that DHCP is being managed by the ORBI and not the "modem".

But the NAS connected to the "modem" has a full set of lights - however, I cannot see it on the network.

So the answer is that ORBI is the master.