pics courtesy of DanC

 

you need this pump from harbor freight or some compressed air

 

clogged drain at each corner





pump to unclog

 

now if you unclogged it and pour water in those drains it should come out in front of the door on each side bottom of A pillar

 

otherwise you may need to pull the drivers kick panel like so to access the drain where it goes through the body

 

it will expose this rubber elbow / grommet be sure it is in place and not torn



to access the pass side follow the instructions to remove the fender vent it will expose this

 

now if everything looks good and water comes in and or runs down the inside A pillar covers the drain tubes might have come off the sunroof or have a hole, either way this will require at least a partial drop of the headliner to access the underside of the sunroof


there are also rear drain tubes not pictured, they run down the C pillars from rear corners of sunroof

 

Added info that might help with drains

https://landroverforums.com/forum/lr3-28/rear-sunroof-drain-locations-lr3-87195/