Disable sprint key (F) while in Triggerbox

Oh I see, but it affects land movement.
Land movement has already 400 normal and 800 max speed.

How can I make this work ONLY while being inside the triggerbox? It’s not realistic to return to a normal walk speed or sprint at 800 while underwater.

I wish the given Blueprints would work, but for some strange reason they don’t work explicitly underwater.