sudo gainroot
vi /home/opt/marble/share/marble/data/maps/earth/openstreetmap/openstreetmap.dgml
<downloadUrl protocol="http" host="a.tah.openstreetmap.org" path="/Tiles/tile/" /> <!-- <downloadUrl protocol="http" host="a.tile.openstreetmap.org" path="/" /> --> <!-- <downloadUrl protocol="http" host="b.tile.openstreetmap.org" path="/" /> --> <!-- <downloadUrl protocol="http" host="c.tile.openstreetmap.org" path="/" /> -->