I will not say anything about the question if this medal is an original or something else, there are much better people in this forum regarding this very complicated field.
What I can say is that the original steel ring and clip have been replaced (if they were there / this was an issued original) by a jeweller who bolted the clip and added a broad suspension. This can be seen if medals were worn often and with time the clip fell off.
Regarding the man (it would be nice to know which Landwehr Bataillon he served in, should be impressed), since he was from Hanover you will have to consult the state archives in Hannover or find someone who has a copy of the medal roll, but won't get too much more info, I am afraid, since he was simply an ordinary soldier.
Perhaps others may add more?
Best