Unable to connect some available interfaces

I have some interfaces that I can not connect:

sudo snap connect clementine:media-hub
error: snap “core” has no “media-hub” interface slots

sudo snap connect anbox:dbus-session-plug
error: snap “core” has no “dbus” interface slots

The interfaces seem to be available for the APP:

snap interfaces clementine
Slot Plug

  •                    clementine:media-hub

snap interfaces anbox
Slot Plug

  •                    anbox:dbus-session-plug

snap --version
snap 2.34.2+18.04
snapd 2.34.2+18.04
series 16
ubuntu 18.04
kernel 4.15.0-22-generic

these slots are likely provided by other snaps you would need to install first …

Ogra is spot on.

While many interfaces are “just” defined by the name alone (because the name implicitly defines the interface type) some interfaces are richer: they can have multiple plugs or slots with different names (but same interface type), and with different attributes. The prime example is content interface which can be composed in almost arbitrary ways. The dbus interface is also like that, it has attributes that define the semantic and also the permissions granted when connected. The media-hub interface feels like a remnant of the Unity 8 work and I don’t think you will find much use for it in practice.