Assuming you are on a through ticket and connecting from F to a flight with no F cabin it is worth asking at lounge check-in if you have access to the F lounge.

I have flown a couple of times Asia-DXB-DUB in F over the last year or so where the DXB-DUB leg has had no F cabin. While my initial DXB-DUB boarding pass has indicated Business lounge access this has been quickly replaced with one showing First class access on both occasions. YMMV.