I set it to 1000m and no matter what after i think 500m it kills the drone as i have gone to far.
I can see the display showing how far i have gone on the screen but thats about it
Seems FP may of hardcoded the distance u can travel.

about 400m it starts to go fuzzy

This is due to the new convar: drone.maxcontrolrange, which defaults to 500. For now, set it to a really high number like 10000. I will be updating the plugin soon to send different values of that convar to each player according to their allowed range.

If you want all players to have the same range, you can just use that convar and uninstall the plugin.

cheers whitethunder