Maybe I'm not being clear. What I'm wondering about is when was this particular version of the Πατερ Υμων written? It is not ancient greek -- and it is not modern greek. But... what is it?
I suggest you start by learning about the various periods of the greek language, maybe start
here.
Or perhaps you may not be aware that the Lord's prayer appears in the Sermon on the Mount, in the Gospel of Matthew, which is part of the New Testament, which was written in Koine, therefore the Lord's prayer is in Koine, in which case Nickel's link is helpful. It will also tell you that there is no "version" of the prayer other than the one you quoted, in mainstream churches who use Greek as their liturgical language. You may find some protestant churches operating in Greece using modern Greek, but the phrase you quoted is not in modern Greek.
Now, the reason you may think that the quoted phrase is in 19th c Greek is because you are probably confusing it with
katharevousa. Even then, the similarity would be only in the quoted phrase and not further on in the prayer, as katharevousa was not an exact copy of Koine.