I wouldn’t worry about water getting in because it will, that and all sorts of other things even if a foam bung as pictured is put in.
What you need is a Connector Bend and Capping 101. Although my only concern is that duct mouth is set a little to far back from the wall so the Connector Bend won’t sit flush over it and against the wall.
Sweet Jesus...after more than 1 hour on hold to ask why was I sent a hub and not the digital phone with it (had selected it when placing the order), I am told that the person I spoke to yesterday should not have placed a separate order for the hub (that's right, I have 2 orders) that I won't get connected any sooner because of it (it's ok as I never got it today anyways) and that they can't see anything from the engineer's end that says my house is ready for service, even when I can see solid green light in the PON part AND to top it off, when the Openreach guys where here today they reconfirmed what I had been told on the phone by them: that everything is ok to proceed!
To make it worst, not only did the man I spoke to seemed to have no clue about when this would change, but could not acknowledge neither the date of when placing the order (17th) the day given to me on the phone by a colleague (tomorrow) nor the day I got by text and email from BT (the 28th). Un-freaking believable!
To make it even worst, the digital phone which I what I had called for, will still make my way next week, but seems that it will do so alongside another hub!!
The guy had no clue why the previous agent had triggered an order for a hub with such urgency, and apologised I didn't get it today (royal mail shows they have not received it from BT anyway).
I thought I was on the end of this. Now seems I'm back on the limbo of "we can't connect you" but with the ticking time bomb of me canceling my 4G mobile broadband yesterday ( which means I will end that service on 10/10) and if I don't have nothing then and cannot connect to work I'm automatically put into disciplinary action by work 🙄🙄♂️