Hi @Nischal ,
Make sure you have the correct Vertices Selected.
It can also be, that you have ‘Double Vertices’. Try M > Merge > By Distance.
It could also be, that the speakers are a Separate Object; you cannot connect Vertices from two different Objects. If that’s the case: in Object Mode, Select the speaker and then SHIFT+Select the console and CTRL+J to Join them.
These are the most likely causes, I think.
