RT-AC87U blocked port(s) ?

Hi - I've got an odd problem - I'm on VirginMedia Cable, I have VM's SuperHub2, an ASUS RT-AC87U, and a T-Mobile/EE Signal-Box (a mini femto-cell)

I was running with the Superhub (in modem-mode) > RT-AC87U > (wired) Signal-Box and all was working fine (I bought the RT-AC87U back in May),
- until last week when the Signal-Box stopped talking back to T-Mobile/EE, and I lost the ability to take/make calls via the Signal-Box.

I tried everything, rebooting all devices, different cables, went...

RT-AC87U blocked port(s) ?